Obstetric outcome in singletons after in vitro fertilization with cryopreserved/thawed embryos

Untangling the independent effect of endometriosis, adenomyosis, and ART-related factors on maternal, placental, fetal, and neonatal adverse outcomes: results from a systematic review and meta-analysis

BACKGROUND

Women with endometriosis may constitute a group at a particularly increased risk of pregnancy-related complications. Furthermore, women selected for assisted reproductive technology (ART) are exposed to additional endocrinological and embryological factors that have been associated with adverse pregnancy outcomes.

OBJECTIVE AND RATIONALE

This study aimed to investigate the independent effect of endometriosis, adenomyosis, and various ART-related factors on adverse maternal, placental, fetal, and neonatal outcomes.

SEARCH METHODS

Published randomized controlled trials, cohort studies, and case-control studies were considered eligible. PubMed, MEDLINE, ClinicalTrials.gov, Embase, and Scopus were systematically searched up to 1 March 2024. This systematic review and meta-analysis was performed in line with the PRISMA and the MOOSE reporting guidelines. To thoroughly investigate the association between endometriosis/adenomyosis and adverse pregnancy outcomes, sub-analyses were conducted, whenever possible, according to: the method of conception (i.e. ART and non-ART conception), the endometriosis stage/phenotype, the coexistence of endometriosis and adenomyosis, any pre-pregnancy surgical treatment of endometriosis, and the form of adenomyosis. The odds ratio (OR) with 95% CI was used as effect measure. The quality of evidence was assessed using the GRADE approach.

OUTCOMES

We showed a higher risk of placenta previa in women with endometriosis compared to controls (34 studies, OR 2.84; 95% CI: 2.47, 3.26; I2 = 83%, moderate quality). The association was observed regardless of the method of conception and was particularly strong in the most severe forms of endometriosis (i.e. rASRM stage III-IV endometriosis and deep endometriosis (DE)) (OR 6.61; 95% CI: 2.08, 20.98; I2 = 66% and OR 14.54; 95% CI: 3.67, 57.67; I2 = 54%, respectively). We also showed an association, regardless of the method of conception, between endometriosis and: (i) preterm birth (PTB) (43 studies, OR 1.43; 95% CI: 1.32, 1.56; I2 = 89%, low quality) and (ii) cesarean section (29 studies, OR 1.52; 95% CI: 1.41, 1.63; I2 = 93%, low quality). The most severe forms of endometriosis were strongly associated with PTB. Two outcomes were associated with adenomyosis both in the main analysis and in the sub-analysis that included only ART pregnancies: (i) miscarriage (14 studies, OR 1.83; 95% CI: 1.53, 2.18; I2 = 72%, low quality) and (ii) pre-eclampsia (7 studies, OR 1.70; 95% CI: 1.16, 2.48; I2 = 77%, low quality). Regarding ART-related factors, the following associations were observed in the main analysis and confirmed in all sub-analyses conducted by pooling only risk estimates adjusted for covariates: (i) blastocyst stage embryo transfer (ET) and monozygotic twinning (28 studies, OR 2.05; 95% CI, 1.72, 2.45; I2 = 72%, low quality), (ii) frozen embryo transfer (FET) and (reduced risk of) small for gestational age (21 studies, OR 0.59; 95% CI, 0.57, 0.61; P < 0.00001; I2 = 17%, very low quality) and (increased risk of) large for gestational age (16 studies, OR 1.70; 95% CI, 1.60, 1.80; P < 0.00001; I2 = 55%, very low quality), (iii) artificial cycle (AC)-FET and pre-eclampsia (12 studies, OR 2.14; 95% CI: 1.91-2.39; I2 = 9%, low quality), PTB (21 studies, OR 1.24; 95% CI 1.15, 1.34; P < 0.0001; I2 = 50%, low quality), cesarean section (15 studies, OR 1.59; 95% CI 1.49, 1.70; P < 0.00001; I2 = 67%, very low quality) and post-partum hemorrhage (6 studies, OR 2.43; 95% CI 2.11, 2.81; P < 0.00001; I2 = 15%, very low quality).

WIDER IMPLICATIONS

Severe endometriosis (i.e. rASRM stage III-IV endometriosis, DE) constitutes a considerable risk factor for placenta previa and PTB. Herein, we recommend against superimposing on this condition other exposure factors that have a strong association with the same obstetric adverse outcome or with different outcomes which, if coexisting, could determine the onset of an ominous obstetric syndrome. Specifically, we strongly discourage the use of AC regimens for FET in ovulatory women with rASRM stage III-IV endometriosis or DE. We also recommend single ET at the blastocyst stage in this high-risk population.

REGISTRATION NUMBER

CRD42023401428.

Cryopreservation, cryoprotectants, and potential risk of epigenetic alteration

The cryopreservation of gametes and embryos has increased notably over the past 20 years and is now an essential part of assisted reproductive technologies (ARTs). However, because the cryopreservation process is un-physiological for human cells, gametes, and embryos, cryobiologists have suggested diverse methods to successfully cryopreserve human gametes and embryos in order to maintain their viability and assure successful pregnancy. During the first period of early development, major waves of epigenetic reprogramming-crucial for the fate of the embryo-occur. Recently, concerns relating to the increased incidence of epigenetic anomalies and genomic-imprinting disorders have been reported after ARTs and cryopreservation. Epigenetic reprogramming is particularly susceptible to environmental and un-physiological conditions such as ovarian stimulation, embryo culture, and cryopreservation that might collectively affect epigenetics dysregulation. Additionally, recent literature suggests that epigenetic and transcriptomic profiles are sensitive to the stress induced by vitrification, osmotic shock, oxidative stress, rapid temperature and pH changes, and cryoprotectants; it is therefore critical to have a more comprehensive understanding of the potential induced perturbations of epigenetic modifications that may be associated with vitrification. The aim of this paper is to present a critical evaluation of the association of gamete and embryo cryopreservation, use of cryoprotectants, and epigenetic dysregulations with potential long-term consequences for offspring health.

Effect of ART treatments on maternal and neonatal outcomes in singleton live births: A large-scale retrospective cohort study

Background

The increased risk of pregnancy complications in the ART population has been reported, but the source of these risks remains controversial. The study aims to evaluate the association between ART treatments and patient characteristics with maternal and neonatal outcomes.

Methods

This was a retrospective analysis of 45,159 singleton pregnant women at a hospital between 2018 and 2021. The maternal and neonatal outcomes included pregnancy-induced hypertension (PIH), preeclampsia (PE), gestational diabetes mellitus (GDM), placental abruption (PA), placenta accreta spectrum (PAS), postpartum hemorrhage (PPH), cesarean section, iatrogenic and spontaneous preterm birth, small for gestational age (SGA), low birth weight (LBW), macrosomia, and birth defects. We assessed the outcomes among the fresh embryo transfer (ET), frozen embryo transfer (FET), and spontaneous conception (SC) groups. Potential risk factors were further analyzed in the ART population.

Results

FET was associated with higher risks for PIH (SC: AOR, 1.97(1.51-2.57); fresh ET: AOR, 1.68(1.03-2.72)), PE (SC: 2.28(1.86-2.80); fresh ET: AOR, 1.61(1.11-2.33)), PAS (SC: AOR, 3.89(3.39-4.46); fresh ET: AOR, 2.23(1.70-2.92)), PPH (SC: AOR, 3.46(2.76-4.34)); fresh ET: 2.09(1.39-3.14)), and macrosomia (SC: 1.53(1.25-1.86); fresh ET: AOR, 2.87(1.89-4.35). Fresh ET was associated with higher risks for PA (SC: AOR, 2.19(1.51-3.18); FET: AOR, 0.39(0.17-0.90)), SGA (SC: AOR, 1.56(1.06-2.31), FET: AOR, 0.42(0.19-0.91)), and LBW (SC: AOR, 2.24(1.82-2.77), FET: AOR, 0.63 (0.44-0.89)), and fresh ET is an independent risk factor for PA and SGA. Furthermore, the risk of GDM was associated with the biological characteristic of low-fertility patients.

Conclusions

Embryo status (fresh or frozen) is a key factor affecting the maternal and neonatal outcomes in ART treatments, while biological characteristics of infertile patients also play a certain role.

Fetal growth after fresh and frozen embryo transfer and natural conception: A population-based register study

OBJECTIVE

To investigate fetal growth trajectories and risks of small and large for gestational age (SGA and LGA), and macrosomia in pregnancies after fresh and frozen embryo transfer (ET), and natural conception (NC).

DESIGN

Longitudinal population-based cohort study.

SETTING

Swedish national registers.

POPULATION

A total of 196 008 singleton pregnancies between 2013 and 2017.

METHODS

Of all singleton pregnancies resulting in live births in the Swedish Pregnancy Register, 10 970 fresh ET, 6520 frozen ET, and 178 518 NC pregnancies with ultrasound data were included. A general least squares model was used to examine the effect of fresh or frozen ET on fetal growth while adjusting for confounders.

MAIN OUTCOME MEASURES

Fetal growth velocity. SGA, LGA and macrosomia.

RESULTS

At 120 days, fetal weights were lower in fresh ET pregnancies compared with NC pregnancies. Thereafter fresh ET as well as FET fetuses had higher fetal weights than NC fetuses, with no differences between themselves until the second trimester. From 210 days, FET fetuses were heavier than fresh ET fetuses, whereas fresh ET fetuses had lower fetal weights than NC fetuses from 245 days. After fresh ET, SGA was more frequent, whereas LGA and macrosomia were less frequent, than after FET.

CONCLUSIONS

This study gives new insights into the differences in fetal growth dynamics between fresh and frozen ET and NC pregnancies. Clinically relevant differences in proportions of SGA, LGA and macrosomia were observed.

Vitrification of human blastocysts for couples undergoing assisted reproduction: an updated review

Over the past 40 years there has been a worldwide critical change in the field of assisted reproduction technology (ART), leading to the increased application of single blastocyst transfer, which is extremely important to avoid the risks of multiple pregnancy and associated complications for both mother and babies. Indeed, advancements in ART over the last few decades have been obtained thanks to several improvements, including ovarian stimulation, embryo culture conditions and, of course, progress in cryopreservation methods, especially with the application of vitrification. The ability to cryopreserve human embryos has improved significantly with vitrification compared to the initially adopted slow-freezing procedures. Since the introduction of vitrification, it has become the gold standard method to effectively cryopreserve human blastocysts. However, some new protocols are now being explored, such as the short warming procedure and even shorter exposure to the equilibration solution before vitrification, which seem to provide optimal results. Therefore, the main aim of the current narrative review, will be to illustrate the benefit of vitrification as an effective method to cryopreserve the human blastocyst and to illustrate new protocols and variations which in future may increase the performance of vitrification protocols.

Successful Fetal Reduction in Early Second Trimester: Series of Three Cases Conceived With Infertility Treatment

This case series explores three instances of a successful fetal reduction in early second-trimester pregnancies conceived through infertility treatments. The patients, all admitted to a central Indian tertiary care hospital, underwent assisted reproductive technologies such as in vitro fertilization (IVF) or intrauterine insemination (IUI). Faced with triplet pregnancies, fetal reduction was made to mitigate risks and enhance maternal and fetal well-being. The reduction procedures, conducted either transvaginally or transabdominally under continuous ultrasound guidance, resulted in the cessation of targeted fetal heart activity and motility. Post-reduction, pregnancies progressed without major complications, culminating in successful deliveries via lower segment cesarean section (LSCS) in the third trimester. This case series underscores the importance of selective fetal reduction in managing pregnancies arising from infertility treatments, emphasizing its role in minimizing risks associated with multiple gestations. Using continuous ultrasound guidance during the reduction procedures proved effective in ensuring precision and safety. These cases contribute valuable insights to the evolving field of reproductive medicine, offering clinicians a nuanced understanding of successful interventions to optimize outcomes in complex pregnancies.

Review of human oocyte cryopreservation in ART programs: Current challenges and opportunities

Oocyte cryopreservation has notably increased in recent times, to become an essential part of clinical infertility treatment. Since the 1980s, many improvements in oocyte cryopreservation (OC) have been adopted, including the great advance with the application of vitrification. The commonly used vitrification protocol applies different cryoprotectants (Ethylene glycol and/or DMSO and/or PROH and sucrose and/or Trehalose) and two different steps: firstly, exposure in equilibration solution for 5-15 min, followed by a vitrification solution for 60-90 s at room temperature. The warming method includes a first step for 1 min at 37 °C and 3 subsequent steps at room temperature to remove the cryoprotectant for a total of 9-12 min. In addition, biosafety is a critical aspect to mention, and it is related to devices used during the vitrification, mainly in terms of whether the biological vitrified material comes in direct contact with liquid nitrogen (open vitrification) or not (closed vitrification), where LN2 may contain potentially contaminating viruses or pathogens. Furthermore, during early development major waves of epigenetic reprogramming take place. Recent literature suggests that epigenetic and transcriptomic profiles are sensitive to the stress induced by vitrification, including osmotic shock, temperature, rapid changes of pH and toxicity of cryoprotectants. It is, therefore, important to better understand the potential perturbations of epigenetic modifications that may be associated with the globally used vitrification methods. Therefore, we here discuss the benefits and efficiency of human oocyte vitrification; we also review the evidence surrounding oocyte cryopreservation-related epigenetic modifications and potential epigenetic dysregulations, together with long-term consequences for offspring health.

Pre-gravid body mass index is associated with a higher risk of gestational hypertension in singleton pregnancy following frozen-thawed embryo transfer

Introduction

Although it is well-known that obesity increases the risk of gestational hypertension (GH) in both spontaneous and assisted reproductive technology (ART) pregnancies. Recent data show that, in ART pregnancies, frozen-thawed embryo transfer (FET) is associated with an even higher risk of GH compared with fresh transfer. However, the relationship between pre-gravid body mass index (BMI) and GH in FET pregnancies has seldom been reported.

Objective

The aim of this study is to examine the effect of pre-gravid BMI on GH in singleton pregnancy following FET.

Methods

A retrospective cohort study at a tertiary hospital, including a total of 7,502 women who achieved singleton pregnancy after FET, was included. All patients were enrolled only once. On the basis of the BMI definitions of the Working Group on Obesity in China (WGOC) and the World Health Organization, the women were divided into normal BMI, overweight, and obese groups. The main outcome was GH, and the effect of pre-pregnancy BMI on GH was assessed by generalized linear model.

Results

The risk of GH in our study population was 6.15%. According to the BMI definitions of the WGOC, the risk of GH in the obese group (15.55%) was significantly higher than that of the overweight group (8.26%, P < 0.001) and the normal BMI group (4.68%, P < 0.001). Pre-gravid overweight and obesity were associated with higher GH risk (OR, 1.77; 95% CI, 1.41-2.20; P < 0.001; OR, 3.69; 95% CI, 2.77-4.91; P < 0.001). A non-linear relationship between pre-gravid BMI and GH was observed. The risk of GH decreased with pre-gravid BMI level up to the turning point of BMI = 28.6 kg/m2 (OR, 1.16; 95% CI, 1.12-1.21; P < 0.001).

Conclusion

Pre-gravid overweight and obesity are associated with higher GH risk among singleton pregnancy following FET. Before the turning point of BMI = 26.8 kg/m2, the risk of GH may increase 16.4% with each one-unit increment of maternal BMI. Women preparing for FET should maintain a normal BMI to lower the chances of GH.

Exploring the effect of cryopreservation in assisted reproductive technology and potential epigenetic risk

Since the birth of the first baby by in vitro fertilization in 1978, more than 9 million children have been born worldwide using medically assisted reproductive treatments. Fertilization naturally takes place in the maternal oviduct where unique physiological conditions enable the early healthy development of the embryo. During this dynamic period of early development major waves of epigenetic reprogramming, crucial for the normal fate of the embryo, take place. Increasingly, over the past 20 years concerns relating to the increased incidence of epigenetic anomalies in general, and genomic-imprinting disorders in particular, have been raised following assisted reproduction technology (ART) treatments. Epigenetic reprogramming is particularly susceptible to environmental conditions during the periconceptional period and non-physiological conditions such as ovarian stimulation, in vitro fertilization and embryo culture, as well as cryopreservation procedure, might have the potential to independently or collectively contribute to epigenetic dysregulation. Therefore, this narrative review offers a critical reappraisal of the evidence relating to the association between embryo cryopreservation and potential epigenetic regulation and the consequences on gene expression together with long-term consequences for offspring health and wellbeing. Current literature suggests that epigenetic and transcriptomic profiles are sensitive to the stress induced by vitrification, in terms of osmotic shock, temperature and pH changes, and toxicity of cryoprotectants, it is therefore, critical to have a more comprehensive understanding and recognition of potential unanticipated iatrogenic-induced perturbations of epigenetic modifications that may or may not be a consequence of vitrification.

Increased Risk of Preeclampsia with Assisted Reproductive Technologies

PURPOSE OF REVIEW

We summarized recent available data to assess the association between assisted reproductive technology (ART) and risk for preeclampsia.

RECENT FINDINGS

The majority of clinical studies supporting the association of preeclampsia and ART are retrospective. Published data from both clinical and pre-clinical studies suggest specific ART procedures may contribute to the increased risk, including in vitro embryo handling and development, hormone stimulation, transfer cycle types, and use of donor oocytes/embryos. Potential mechanisms include epigenetic aberrations leading to abnormal placentation, absence of factors secreted by the corpus luteum, and immunologic responses to allogenic gametes. There is an increased risk of preeclampsia following ART. Treatment plans that favor reduced preeclampsia risk should be considered for ART pregnancies. To make ART pregnancies safer, additional clinical and animal model studies are needed to elucidate the underpinnings of this risk association.

Effects of reduced follicle-stimulating hormone dosage before human chorionic gonadotropin trigger on in vitro fertilization outcomes

OBJECTIVE

To determine whether a reduced dose of follicle-stimulating hormone (FSH) before human chorionic gonadotropin (hCG) trigger during ovarian stimulation can affect in vitro fertilization (IVF) outcomes.

METHODS

This study included 347 patients with a normal ovarian response who received a reduced dose of FSH before hCG trigger for 2-3 days (Group A) and 671 patients who did not receive a reduced dose (Group B) from a university-affiliated IVF center between January 2021 and December 2022. The primary endpoint was estrogen (E2) and progesterone (P) levels on the day of hCG trigger, fresh embryo transfer cycles, laboratory outcomes, and clinical outcomes between the two groups.

RESULTS

On the day of hCG trigger, Group A had significantly lower E2 and P levels than those in Group B (3454.95 ± 1708.14 pg/mL versus 3798.70 ± 1774.26 pg/mL, p = 0.003; and 1.23 ± 0.53 ng/mL versus 1.37 ± 0.59 ng/mL, p < 0.001, respectively). The proportion of patients with P levels ≥ 1.5 ng/mL was 22.48% in Group A compared to 34.58% in Group B (p < 0.001), while the proportion of patients with E2 ≥ 5000 pg/mL was 15.27% in Group A compared to 25.93% in Group B (p < 0.001). The fresh embryo-transfer cycle rate in Group A was higher than that in group B (54.47% and 32.64%, respectively; p < 0.001). Despite the reduction in FSH dosage, there were no significant differences between groups regarding the number of oocytes retrieved, total number of mature oocytes, normal fertilization rate, cleavage rate, Day 3 top-quality rate, implantation rate, pregnancy rate per cycle, and early pregnancy loss rate.

CONCLUSION

While a reduced dose of FSH prior to hCG trigger during ovarian stimulation did not significantly affect IVF outcomes, it was associated with lower E2 and P levels, resulting in fewer cycles with E2 ≥ 5000 pg/mL and P ≥ 1.5 ng/mL on the day of the hCG trigger.

Clinical pregnancy rate for frozen embryo transfer with HRT: a randomized controlled pilot study comparing 1 week versus 2 weeks of oestradiol priming

RESEARCH QUESTION

Does a frozen-embryo transfer in an artificially-prepared endometrium (FET-HRT) cycle yield similar clinical pregnancy rate with 7 days of oestrogen priming compared to 14 days?

DESIGN

This is a single-centre, randomized, controlled, open-label pilot study. All FET-HRT cycles were performed in a tertiary centre between October 2018 and January 2021. Overall, 160 patients were randomized, with a 1:1 allocation, into two groups of 80 patients each: group A (7 days of E2 prior to P4 supplementation) and group B (14 days of E2 prior to P4 supplementation). Both groups received single blastocyst stage embryos on the 6th day of vaginal P4 administration. The primary outcome was the feasibility of such strategy assessed as clinical pregnancy rate, secondary outcomes were biochemical pregnancy rate, miscarriage rate, live birth rate and serum hormone levels on the day of FET. Chemical pregnancy was assessed by an hCG blood test 12 days after FET and clinical pregnancy was confirmed by transvaginal ultrasound at 7 weeks.

RESULTS

The analysis included 160 patients who were randomly assigned to either group A or group B on the seventh day of their FET-HRT cycle if the measured endometrial thickness was above 6.5 mm. Following screening failures and of drop-outs, 144 patients were finally included both in group A (75 patients) or group B (69 patients). Demographic characteristics for both groups were comparable. The biochemical pregnancy rate was 42.5% and 48.8% for group A and group B, respectively (p 0.526). Regarding the clinical pregnancy rate at 7 weeks, no statistical difference was observed (36.3% vs 46.3% for group A and group B, respectively, p = 0.261). The secondary outcomes of the study (biochemical pregnancy, miscarriage, and live birth rate) were comparable between the two groups for IIT analysis, as well as the P4 values on the day of FET.

CONCLUSIONS

In a frozen embryo transfer cycle, performed with artificial preparation of the endometrium, 7 versus 14 days of oestrogen priming are comparable, in terms of clinical pregnancy rate; the advantages of a seven-day protocol include the shorter time to pregnancy, reduced exposure to oestrogens, and more flexibility of scheduling and programming, and less probability to recruit a follicle and have a spontaneous LH surge. It is important to keep in mind that this study was designed as a pilot trial with a limited study population as such it was underpowered to determine the superiority of an intervention over another; larger-scale RCTs are warranted to confirm our preliminary results.

TRIAL REGISTRATION

Clinical trial number: NCT03930706.

Can Cryopreservation in Assisted Reproductive Technology (ART) Induce Epigenetic Changes to Gametes and Embryos?

Since the birth of Louise Brown in 1978, more than nine million children have been conceived using assisted reproductive technologies (ARTs). While the great majority of children are healthy, there are concerns about the potential epigenetic consequences of gametes and embryo manipulation. In fact, during the preimplantation period, major waves of epigenetic reprogramming occur. Epigenetic reprogramming is susceptible to environmental changes induced by ovarian stimulation, in-vitro fertilization, and embryo culture, as well as cryopreservation procedures. This review summarizes the evidence relating to oocytes and embryo cryopreservation and potential epigenetic regulation. Overall, it appears that the stress induced by vitrification, including osmotic shock, temperature and pH changes, and toxicity of cryoprotectants, might induce epigenetic and transcriptomic changes in oocytes and embryos. It is currently unclear if these changes will have potential consequences for the health of future offspring.

Fresh Compared With Frozen Embryo Transfer and Risk of Severe Maternal Morbidity: A Study of In Vitro Fertilization Pregnancies in Ontario, Canada

OBJECTIVES

To quantify the risk of severe maternal morbidity (SMM) in fresh versus frozen-thawed embryo transfers (ETs) among pregnancies conceived by in vitro fertilization and to assess SMM risk according to the number of fresh ETs prior to the index pregnancy.

METHODS

Retrospective cohort study using the provincial birth registry in Ontario, Canada. We included 13 929 individuals aged 18-55 years who conceived via in vitro fertilization between January 1, 2013, and March 5, 2018, and delivered a live or stillborn infant ≥20 weeks gestation. We compared the primary outcome, a composite of SMM or death, between fresh and frozen ETs.

RESULTS

A total of 174 individuals who conceived via fresh ETs had SMM (30.7 per 1000), compared with 280 among individuals who received frozen ETs (33.9 per 1000); adjusted risk ratio (aRR) 0.85 (95% CI 0.70-1.04). Compared with frozen ET, fresh ET was associated with a lower risk of severe hemorrhage (aRR 0.63; 95% CI 0.48-0.82) but no difference in risk of preeclampsia. Among individuals with 1 (n = 211) or ≥2 (n = 88) prior fresh cycles, the risk of SMM was not increased compared with having no prior cycles; aRR 0.96 (95% CI 0.78-1.18) and 0.91 (95% CI 0.67-1.25), respectively.

CONCLUSION

Fresh ET was associated with a lower risk of severe hemorrhage compared with frozen ET. These findings may be partly explained by the increased popularity of a freeze-all strategy, reserving fresh ETs for patients with fewer comorbidities.

The impact of different endometrial preparation protocols on obstetric and neonatal complications in frozen-thawed embryo transfer: a retrospective cohort study of 3,458 singleton deliveries

BACKGROUND

Frozen-thawed embryo transfer (FET) is thought to be associated with obstetric and neonatal complications after in vitro fertilization/intracytoplasmic single sperm injection (IVF/ICSI) treatment. The study aimed to determine whether the endometrial preparation protocol is an influencing factor for these complications.

METHODS

We conducted a retrospective cohort study of 3,458 women who had singleton deliveries after IVF/ICSI-FET treatment at the Centre for Reproductive Medicine of Shanghai First Maternity and Infant Hospital between July 2016 and April 2021. The women were divided into three groups according to the endometrial preparation protocols: 2,029 women with programmed cycles, 959 with natural cycles, and 470 with minimal ovarian stimulation cycles. The primary outcomes were the incidence rates of obstetric and neonatal complications, namely, hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM), intrahepatic cholestasis of pregnancy (ICP), placenta previa, preterm rupture of membranes (PROM), preterm delivery, postpartum haemorrhage, large for gestational age (LGA), small for gestational age (SGA), and macrosomia.

RESULTS

After adjustments for confounding variables by multivariate logistic regression analysis, the results showed that programmed cycles had an increased risk of HDP (aOR = 1.743; 95% CI, 1.110-2.735; P = 0.016) and LGA (aOR = 1.269; 95% CI, 1.011-1.592; P = 0.040) compared with natural cycles. Moreover, programmed cycles also increased the risk of LGA (aOR = 1.459; 95% CI, 1.083-1.965; P = 0.013) but reduced the risk of SGA (aOR = 0.529; 95% CI, 0.348-0.805; P = 0.003) compared with minimal ovarian stimulation cycles. There were no significant differences between natural cycles and minimal ovarian stimulation cycles.

CONCLUSIONS

During IVF/ICSI-FET treatment, the risk of HDP and LGA was increased in women with programmed cycles. Therefore, for patients with thin endometrium, irregular menstruation or no spontaneous ovulation, minimal ovarian stimulation cycles may be a relatively safer option than programmed cycles.

Factors associated with large-for-gestational-age infants born after frozen embryo transfer cycles

Objective

To examine trends of frozen embryo transfer (FET) proportions and large-for-gestational-age (LGA) incidence and determine risk factors for LGA infants after FET.

Design

Retrospective cohort study.

Setting

Not applicable.

Patients

Frozen embryo transfer cycles.

Interventions

None.

Main Outcome Measures

Singleton LGA infant.

Results

The percentage of FETs increased from 20%-74% of transfers, whereas the rate of LGA among FET singleton births decreased from 18%-12% during 2004-2018. In a subanalysis of 127,525 FET-associated singleton live births during 2016-2018, patient factors associated with LGA were higher-than-normal maternal body mass index (body mass index [BMI], 25.0-29.9 kg/m²; adjusted relative risk [aRR], 1.31; 95% confidence interval [CI], 1.26-1.36; BMI, 30.0-34.9 kg/m²; aRR, 1.48; 95% CI, 1.41-1.55; and BMI, >35 Kg/m²; aRR, 1.68; 95% CI, 1.59-1.77) and ≥1 prior birth vs. none. Low maternal BMI (<18.5 vs. 18.5-24.9 kg/m²) and cycles involving patients who were non-Hispanic (NH) Asian/Native Hawaiian/Pacific Islander, NH Black, or Hispanic (compared with NH White) were at lower risk of LGA infants. Cycle factors associated with LGA included gestational carrier use (aRR, 1.25; 95% CI, 1.16-1.34) and donor sperm (aRR, 1.17; 95% CI, 1.10-1.25).

Conclusions

Although the number and proportion of FET cycles increased from 2004-2018, the rate of LGA after FET decreased. Maternal BMI, parity, and race/ethnicity were the strongest risk factors for LGA infants after FET.

Reproductive, obstetric, and long-term health outcome after uterus transplantation: results of the first clinical trial

OBJECTIVE

To evaluate reproductive, obstetric, and long-term health of the first completed study of uterus transplantation (UTx).

DESIGN

Prospective.

SETTING

University hospital.

PATIENT(S)

Nine live donor UTx procedures were conducted and seven were successful. Donors, recipients, and children born were observed.

INTERVENTION(S)

In vitro fertilization was performed with embryo transfer (ET) of day 2 or day 5 embryos in natural cycles. Pregnancies and growth trajectory of the children born were observed. Health-related quality of life, psychosocial outcome, and medical health of donors and recipients were evaluated by questionnaires.

MAIN OUTCOME MEASURE(S)

The results of in vitro fertilization, pregnancies, growth of children, and long-term health of patients were reported.

RESULT(S)

Six women delivered nine infants, with three women giving birth twice (cumulative birth rates of 86% and 67% in surgically successful and performed transplants, respectively). The overall clinical pregnancy rate (CPR) and live birth rate (LBR) per ET were 32.6% and 19.6%, respectively. For day 2 embryos, the CPR and LBR per ET were 12.5% and 8.6%, respectively. For day 5 embryos, the CPR and LBR per ET were 81.8% and 45.4%, respectively. Fetal growth and blood flow were normal in all pregnancies. Time of delivery (median in full pregnancy weeks + days [ranges]) by cesarean section and weight deviations was 35 + 3 (31 + 6 to 38 + 0) and -1% (-13% to 23%), respectively. Three women developed preeclampsia and four neonates acquired respiratory distress syndrome. All children were healthy and followed a normal growth trajectory. Measures of long-term health in both donors and recipients were noted to be favorable. When UTx resulted in a birth, scores for anxiety, depression, and relationship satisfaction were reassuring for both the donors and recipients.

CONCLUSION(S)

The results of this first complete UTx trial show that this is an effective infertility treatment, resulting in births of healthy children and associated with only minor psychological and medical long-term effects for donors and recipients.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02987023.

Adverse impact of elevated progesterone levels on human chorionic gonadotropin trigger day on blastocyst transfer outcomes in gonadotropin-releasing hormone agonist cycles

OBJECTIVE

Dose an elevated serum progesterone (P) level on the human chorionic gonadotropin (hCG) trigger day have a negative effect on clinical pregnancy outcomes for embryos transferred at different stages of development in long-acting gonadotropin-releasing hormone agonist (GnRHa) in vitro fertilization-embryo transfer (IVF-ET) cycles?

STUDY DESIGN

This was a noninterventional, retrospective, observational, single-centre cohort study. A total of 1951 patients received long-acting GnRHa for pituitary downregulation in IVF-ET cycles at Nanjing Drum Tower Hospital from January 2018 to December 2020. The serum P levels on the day of hCG administration were measured, together with other cycle parameters, to explore the relationship between P levels and the clinical pregnancy rate (CPR) of different embryos transferred.

RESULTS

When the serum P level on the hCG day was higher than 1.5 ng/mL, the CPR did not decrease significantly. There was no correlation between the CPR of cleavage-stage embryo transfer and the serum P level on the hCG day. In addition, the interaction analysis suggested that the CPR of patients undergoing blastocyst transfer decreased as serum P levels on the hCG day increased. Progesterone levels on the day of hCG administration were closely related to the CPR of blastocyst transfer rather than cleavage-stage embryo transfer.

CONCLUSION

An increased serum P level on the day of hCG administration did not affect the CPR of cleavage-stage embryo transfer, but it reduced the CPR of blastocyst transfer cycles.

Greater estimated fetal weight and birth weight in IVF/ICSI pregnancy after frozen-thawed vs fresh blastocyst transfer: prospective cohort study with novel unified modeling methodology

OBJECTIVE

To compare, using a unified approach, standardized estimated fetal weight (EFW) trajectories from the second trimester to birth and birth-weight (BW) measurements in in-vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) pregnancies obtained after frozen-thawed vs fresh blastocyst transfer (BT).

METHODS

This was a secondary analysis of a prospective longitudinal cohort study performed at the Fetal Medicine and Obstetric Departments of San Raffaele Hospital in Milan, Italy, from January 2016 to December 2020. Eligible for inclusion were singleton viable gestations conceived by autologous IVF/ICSI conception after fresh or frozen-thawed BT that underwent standard fetal biometry assessment at 19-41 weeks and had BW measurements available. All ultrasound assessments were performed by operators blinded to the employment of cryopreservation. Patients with twin gestation, significant pregestational disease, miscarriage, major fetal abnormalities and use of other types of medically assisted reproduction techniques were excluded. EFW and BW Z-scores and their trajectories were analyzed using general linear models (GLM) and logistic regression with a unified modeling methodology based on the Fetal Medicine Foundation fetal and neonatal population weight charts, adjusting for major confounders. Differences between prenatal EFW and postnatal BW centiles in the two groups were assessed and compared using contingency tables, χ² test and conversion of prenatal to postnatal centiles.

RESULTS

A total of 631 IVF/ICSI pregnancies were considered, comprising 263 conceived following fresh BT and 368 after frozen-thawed BT. A total of 1795 EFW observations were available (n = 715 in fresh BT group and n = 1080 in frozen-thawed BT group; median of three observations per patient). EFW and BW < 10^th centile were significantly more frequent in the fresh than in the frozen-thawed BT group (P = 0.003 and P < 0.001, respectively). EFW and BW > 90^th centile were significantly more frequent in the frozen-thawed vs fresh BT group (P = 0.034 and P = 0.002, respectively). GLM showed significantly decreasing EFW Z-scores with advancing gestational age (GA) in both groups. The effect of GA was assumed to be equal in the two study groups, as no significant interaction effect was found. Smoothed mean EFW Z-scores from 19 weeks of gestation to term and smoothed mean BW Z-scores were both significantly higher in the frozen-thawed compared with the fresh BT group (EFW Z-score, 0.70 ± 1.29 vs 0.28 ± 1.43; P < 0.001; BW Z-score, 0.04 ± 1.08 vs -0.31 ± 1.28; P < 0.001). Mean smoothed EFW Z-score values in the frozen-thawed vs fresh BT groups were 1.01 ± 0.12 vs 0.60 ± 0.08 at 19-27 weeks, 0.36 ± 0.07 vs -0.06 ± 0.04 at 28-35 weeks and -0.66 ± 0.01 vs -0.88 ± 0.02 at 36-41 weeks. Mean smoothed BW Z-score values in the frozen-thawed vs fresh BT groups were -0.80 ± 0.14 vs -1.20 ± 0.10 at 28-35 weeks and 0.22 ± 0.16 vs -0.24 ± 0.14 at 36-41 weeks. Assessment of EFW and BW concordance showed a significantly greater rate of postnatal confirmation of prenatally predicted small-for-gestational age (SGA) < 10^th centile in the fresh compared with the frozen-thawed BT group (P < 0.001), whereas the rate of postnatal confirmation of large-for-gestational age (LGA) > 90^th centile was significantly higher in the frozen-thawed vs the fresh BT group (P < 0.001). Logistic regression analysis showed that the smoothed rate of EFW < 3^rd centile was about 6-fold higher in the fresh vs frozen-thawed BT group (P < 0.001), whereas the smoothed rates of EFW 90^th -97^th centile and > 97^th centile were nearly double in the frozen-thawed compared with the fresh BT group (P < 0.05 and P < 0.001, respectively).

CONCLUSIONS

Robust novel unified prenatal-postnatal modeling in IVF/ICSI pregnancies after frozen-thawed or fresh BT from 19 weeks of gestation to birth showed non-divergent growth trajectories, with higher EFW and BW Z-scores in the frozen-thawed vs fresh BT group. The mean EFW Z-scores in both IVF/ICSI groups were greater than those expected for natural conceptions, being highest in the midtrimester and decreasing with advancing gestation in both groups, becoming negative after 32 weeks in the fresh and after 35 weeks in the frozen-thawed BT group. Mean BW Z-scores were negative in both groups, with lower values in preterm fetuses, and increased with advancing gestation, becoming positive at term in the frozen-thawed BT group. IVF/ICSI conceptions from frozen-thawed as compared to fresh BT presented increased rate of LGA and reduced rate of SGA both prenatally and postnatally. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Embryo cryopreservation leads to sex-specific DNA methylation perturbations in both human and mouse placentas

In vitro fertilization (IVF) is associated with DNA methylation abnormalities and a higher incidence of adverse pregnancy outcomes. However, which exposure(s), among the many IVF interventions, contributes to these outcomes remains unknown. Frozen embryo transfer (ET) is increasingly utilized as an alternative to fresh ET, but reports suggest a higher incidence of pre-eclampsia and large for gestational age infants. This study examines DNA methylation in human placentas using the 850K Infinium MethylationEPIC BeadChip array obtained after 65 programmed frozen ET cycles, 82 fresh ET cycles and 45 unassisted conceptions. Nine patients provided placentas following frozen and fresh ET from consecutive pregnancies for a paired subgroup analysis. In parallel, eight mouse placentas from fresh and frozen ET were analyzed using the Infinium Mouse Methylation BeadChip array. Human and mouse placentas were significantly hypermethylated after frozen ET compared with fresh. Paired analysis showed similar trends. Sex-specific analysis revealed that these changes were driven by male placentas in humans and mice. Frozen and fresh ET placentas were significantly different from controls, with frozen samples hypermethylated compared with controls driven by males and fresh samples being hypomethylated compared with controls, driven by females. Sexually dimorphic epigenetic changes could indicate differential susceptibility to IVF-associated perturbations, which highlights the importance of sex-specific evaluation of adverse outcomes. Similarities between changes in mice and humans underscore the suitability of the mouse model in evaluating how IVF impacts the epigenetic landscape, which is valuable given limited access to human tissue and the ability to isolate specific interventions in mice.

Comparison of perinatal outcomes after frozen or fresh embryo transfer: separate analyses of singleton, twin, and sibling live births from a linked national in vitro fertilization registry

OBJECTIVE

To determine whether perinatal outcomes following frozen vs. fresh embryo transfer (ET) differ within singletons, within sets of twins, and between siblings.

DESIGN

Population-based retrospective cohort study.

SETTING

Academic Medical School PATIENT(S): 200,075 live births in 151,561 women who underwent in vitro fertilization with frozen or fresh ET between 1992 and 2017.

MAIN OUTCOME MEASURE(S)

Gestational age at birth, birthweight, congenital anomaly, and healthy baby (≥37 weeks of gestation, birthweight 2,500-4,000 g, no congenital malformations).

RESULT(S)

There were 200,075 live births in 151,561 women including 132,679 singletons, 33,698 sets of twins, and 5,723 pairs of singleton siblings. In singletons, frozen ET was associated with a lower risk of very preterm birth (adjusted relative risk [aRR], 0.83; 95% confidence interval [CI], 0.73, 0.94), preterm birth (aRR, 0.93; 95% CI, 0.88, 0.97), low birthweight (<2,500 g) (aRR, 0.72; 95% CI, 0.68, 0.77), small for gestational age (aRR, 0.66; 95% CI, 0.62, 0.70) and congenital anomaly (aRR, 0.85; 95% CI, 0.78, 0.94), but higher risk of high birthweight (>4,000 g) (aRR, 1.64; 95% CI, 1.58, 1.72) and large for gestational age (aRR, 1.62; 95% CI, 1.55, 1.70) in comparison with fresh ET. In twins, frozen ET was associated with lower risk of very preterm birth (aRR, 0.84; 95% CI, 0.73, 0.97), and low birthweight (aRR, 0.72; 95% CI, 0.68, 0.77), but with a higher chance of a healthy baby (aRR, 1.11; 95% CI, 1.06, 1.16) compared to fresh ET. Singletons conceived following frozen ET had a lower risk of low birthweight (aRR, 0.56; 95% CI, 0.44, 0.74) and being small for gestational age (aRR, 0.54; 95% CI, 0.42, 0.68) than a singleton sibling born after a fresh ET. Frozen ET also was associated with higher risk of high birthweight (aRR, 1.85; 95% CI, 1.54, 2.24) and being large for gestational age (aRR, 1.81; 95% CI, 1.50, 2.20), and also were less likely to be preterm (aRR, 0.81; 95% CI, 0.67, 0.99).

CONCLUSION(S)

Our key finding is that singletons born following a frozen ET are less likely to be small for gestational age than a singleton sibling born following fresh ET but are more likely to be large for gestational age.

Association of maternal pre-pregnancy body mass index with birth weight and preterm birth among singletons conceived after frozen-thawed embryo transfer

BACKGROUND

To explore the effect of pre-pregnancy body mass index (BMI) on neonatal outcomes among singletons born after frozen embryo transfer (FET).

METHODS

This large retrospective cohort study included 18,683 singleton infants born after FET during the period from Jan 1, 2007 to Dec 31, 2019. The main outcomes were large for gestational age (LGA) and preterm birth. Logistic regression models with generalized estimating equations for clustering by patients to estimate odds ratios of LGA and preterm birth.

RESULTS

Overweight was positively associated with LGA overall (adjusted OR 1.78 [95%CI 1.60-1.98]), and this association was consistent across age categories. The underweight was inversely associated with LGA among mothers younger than 35 years (adjusted OR 0.49 [95%CI 0.39-0.62] among mothers younger than 30 years; adjusted OR 0.47 [95%CI 0.37-0.60] among mothers aged 30-34 years), but this association was no significant among mothers 35 years or older. Overweight was positively and significantly associated with preterm birth overall (adjusted OR 1.52 [95%CI 1.30-1.77]) and consistently across age categories. The underweight mothers younger than 30 years had a decreased risk of preterm birth (adjusted OR 0.70 [95%CI 0.51-0.97]), but the underweight was no significantly associated with preterm birth among women aged 30 years of older.

CONCLUSIONS

The risks of LGA and preterm birth were increased in singletons born to overweight mothers, regardless of the maternal age. Underweight decreased the risk of LGA and preterm birth for younger mothers. These findings are important for providing preconceptional counseling to specifically targeted women at high risk of LGA and preterm birth.

Should any use of artificial cycle regimen for frozen-thawed embryo transfer in women capable of ovulation be abandoned: yes, but what's next for FET cycle practice and research?

Over the past decade, the use of frozen-thawed embryo transfer (FET) treatment cycles has increased substantially. The artificial ('programmed') cycle regimen, which suppresses ovulation, is widely used for that purpose, also in ovulatory women or women capable of ovulation, under the assumption of equivalent efficacy in terms of pregnancy achievement as compared to a natural cycle or modified natural cycle. The advantage of the artificial cycle is the easy alignment of the time point of thawing and transferring embryos with organizational necessities of the IVF laboratory, the treating doctors and the patient. However, recent data indicate that pregnancy establishment under absence of a corpus luteum as a consequence of anovulation may cause relevant maternal and fetal risks. Herein, we argue that randomized controlled trials (RCTs) are not needed to aid in the clinical decision for or against routine artificial cycle regimen use in ovulatory women. We also argue that RCTs are unlikely to answer the most burning questions of interest in that context, mostly because of lack of power and precision in detecting rare but decisive adverse outcomes (e.g. pre-eclampsia risk or long-term neonatal health outcomes). We pinpoint that, instead, large-scale observational data are better suited for that purpose. Eventually, we propose that the existing understanding and evidence is sufficient already to discourage the use of artificial cycle regimens for FET in ovulatory women or women capable of ovulation, as these may cause a strong deviation from physiology, thereby putting patient and fetus at avoidable health risk, without any apparent health benefit.

Potential role of the corpus luteum in maternal cardiovascular adaptation to pregnancy and preeclampsia risk

Studies in the gravid rat model revealed a key role for the corpus luteal hormone, relaxin, in the maternal circulatory changes of early pregnancy epitomized by profound systemic vasodilation and increased arterial compliance. To determine whether the corpus luteum may play a similar role in human pregnancy, women who conceived by in vitro fertilization were studied. Implementation of artificial (programmed) cycles for embryo transfers, which precluded the formation of a corpus luteum, was associated with notable attenuation of the gestational rise in cardiac output and fall in carotid-femoral pulse wave velocity (reflecting impairment of arterial dilation and increased compliance, respectively) and deficiencies in other cardiovascular changes normally observed during the first trimester. Cardiac output and carotid-femoral pulse wave velocity were restored after the first trimester of pregnancy, consistent with rescue by placental vasodilators, such as placental growth factor. In addition, a potential role of corpus luteal factors in reducing the risk of developing preeclampsia was hypothesized. In most single and multiple center, prospective and retrospective cohort (and registry) studies, the risk of developing preeclampsia and preeclampsia with severe features was increased specifically in women undergoing autologous frozen embryo transfer in artificial cycles without the formation of a corpus luteum relative to natural, modified natural, stimulated, or controlled ovarian stimulation cycles and spontaneous pregnancies-all associated with the formation of at least 1 corpus luteum. Taken together, these observational studies are sufficiently compelling to warrant randomized clinical trials comparing preeclampsia risk in autologous frozen embryo transfer in natural vs artificial cycles. Impaired endometrial function because of suboptimal hormonal administration is an alternative but not mutually exclusive explanation for increased preeclampsia risk in autologous frozen embryo transfer in artificial cycles. Potential mechanisms by which the corpus luteum may reduce the risk of developing preeclampsia and whether autologous frozen embryo transfer in artificial cycles is associated with increased risk of preterm preeclampsia, term preeclampsia, or both are discussed. Last, suggestions for future investigations are noted.

Association Between Fresh Embryo Transfers and Frozen-Thawed Embryo Transfers Regarding Live Birth Rates Among Women Undergoing Long Gonadotropin-Releasing Hormone Antagonist Protocols

Background: The availability and use of frozen-thawed embryos after controlled ovarian hyperstimulation for assisted reproduction have increased with improvements in vitrification techniques and the rise of gonadotropin-releasing hormone (GnRH) antagonist protocols. Although evidence has shown that frozen-thawed embryo transfers (FETs) result in higher live birth rates than fresh embryo transfers, it is uncertain whether this association exists in cycles employing the GnRH antagonist protocol. Objective: To test the hypothesis that FETs are more likely to result in a live birth than fresh embryo transfers in a GnRH antagonist protocol cycle and to investigate whether frozen blastocyst transfer increases live birth rates compared to fresh blastocyst transfer. Design: A retrospective historical cohort study was conducted using data collected from the Department of Reproductive Medicine of Liuzhou Maternity and Child Healthcare Hospital for 1,437 patients who underwent the GnRH antagonist protocol between 1 January 2015, and 31 December 2020. The primary outcome was the live birth rate, which was compared between fresh embryo transfer and FET, and the secondary outcomes were clinical pregnancy rate and miscarriage rate, which were compared between the two groups. Analyses were adjusted to account for the age of the patient, number of embryo transfers, day of embryo transfer, and type of infertility. Results: Fresh embryo transfers accounted for 1,026 (71.4%) of the 1,437 patients who underwent the GnRH antagonist protocol in our analysis, while FETs accounted for 411 (28.6%). Patients with fresh and frozen-thawed embryos had comparable median body mass index (body mass index; 22.3 [IQR, 24.6-20.0] vs. 22.0 [IQR, 24.5-19.9]). There was a significant difference in the median age of the fresh embryo transfer group (34.0 [IQR, 39.0-30.0]) and the Frozen-thawed embryo transfer group (32.0 [IQR, 37.0-29.0]). Blastocysts were transferred in 14.6% of the fresh embryo transfer cycles and 45.5% of the FET cycles, whereas they account for 10.4% and 13.0% of all patients, respectively. The mean number of embryos transferred was 2 (IQR, 2.0-1.0) for the fresh embryo transfer group and 1 (IQR, 2.0-1.0) for the FET group, with a significant difference in the mean number of embryos transferred. The live birth rate after fresh embryo transfer vs. FET was 28.7% vs. 34.5% (absolute difference, 5.9%; adjusted relative risk [aRR], 1.15 [95% CI, 0.88-1.51]). The clinical pregnancy rates were 39.9% vs. 46.0%, respectively (absolute difference, 6.1%; aRR, 1.10 [95% CI, 0.85-1.43]). The miscarriage rates were 22.5% vs. 23.8%, respectively (absolute difference, 1.3%; aRR, 1.13 [95% CI, 0.75-1.70]). Conclusion: In this retrospective study of women who underwent assisted reproduction using GnRH antagonists, FETs resulted in a higher live birth rates and clinical pregnancy rates than fresh embryo transfers, which parts of these differences were attributable to embryo stage. However, the interpretation of the findings is limited by the possibility of selection and confounding biases.

The vanishing twin: Diagnosis and implications

Vanishing twin syndrome (VTS), defined by first-trimester spontaneous loss of a twin, is a common phenomenon with a reported prevalence of 15-35% of twin pregnancies. The etiology of VTS is obscure. Still, several risk factors have been identified, including an increased number of embryos transferred in pregnancies conceived by in vitro fertilization, an initial increased number of gestational sacs and advanced maternal age. The effect of VTS on obstetric and perinatal outcomes is controversial. Several studies have reported that pregnancies with VTS were associated with increased risk for preterm birth and small for gestational age neonates compared to singleton pregnancies, while others showed no difference in perinatal outcomes. The prevalence of placental vascular and anatomic abnormalities such as small placentas was higher in VTS. These findings lay an essential foundation for understanding how this phenomenon affects obstetric and perinatal outcomes of the surviving pregnancy.

Placenta Accreta Spectrum Disorder Complicated with Endometriosis: Systematic Review and Meta-Analysis

This study aimed to assess the relationship between placenta accreta spectrum disorder (PASD) and endometriosis. The relationships among pregnancy, assisted reproductive technology (ART), placenta previa, ART-conceived pregnancy and PASD were also determined. A systematic literature review was conducted using multiple computerized databases. Forty-eight studies (1990–2021) met the inclusion criteria. According to the adjusted pooled analysis (n = 3), endometriosis was associated with an increased prevalence of PASD (adjusted odds ratio [OR] 3.39, 95% confidence interval [CI] 1.96–5.87). In the included studies, the ART rate ranged from 18.2% to 37.2% for women with endometriosis. According to the adjusted pooled analysis, women who used ART were more likely to have placenta previa (n = 13: adjusted OR 2.96, 95%CI, 2.43–3.60) and PASD (n = 4: adjusted OR 3.54, 95%CI 1.86–6.76) than those who did not use ART. According to the sensitivity analysis using an unadjusted analysis accounting for the type of ART, frozen embryo transfer (ET) was associated with an increased risk of PASD (n = 4: OR 2.79, 95%CI, 1.22−6.37) compared to fresh ET. Endometriosis may be associated with an increased rate of PASD. Women with placenta previa complicated with endometriosis who conceived using frozen ET may be a high risk for PASD.

Pregnancy Outcomes After Frozen-Thawed Embryo Transfer in the Absence of a Corpus Luteum

Background: Nowadays, frozen-thawed embryo transfer (FET) cycles represent a high proportion of fertility treatments worldwide. Recent studies suggest differences in pregnancy outcomes depending on the FET treatment protocol used. The reason for this is still unclear, but the number of corpora lutea (CL) at conception is discussed as a possible factor. This study aims to investigate whether maternal and neonatal outcomes for pregnancies following FET lacking a CL differ from FET with one or more CL in order to explore a potential link between CL absence and adverse pregnancy outcomes.

Methods: The study was designed as a retrospective, multi-center observational study with two cohorts after singleton live birth [0 CL cohort (FET in a programmed cycle, n = 114) and ≥ 1 CL cohort (FET in a natural or stimulated cycle, n = 68)]. Participants completed a questionnaire on the outcome of pregnancy and birth records were analyzed in a descriptive way. Multivariable logistic and linear regressions were performed in order to explore associations between CL absence and pregnancy outcomes. The strength of the agreement between the information in the survey and the diagnoses extracted from the files was assessed by Cohen's Kappa.

Results: The risk of hypertensive disorders of pregnancy was higher after FET in the absence of a CL compared to FET with CL presence (aOR 5.56, 95% CI 1.12 – 27.72). Birthweights and birthweight percentiles were significantly higher in the 0 CL group. CL absence was a predictor of higher birthweight (adjusted coefficient B 179.74, 95% CI 13.03 – 346.44) and higher birthweight percentiles (adjusted coefficient B 10.23, 95%, 95% CI 2.28 – 18.40) particularly in female newborns of the 0 CL cohort. While the strength of the agreement between the reported information in the survey and the actual diagnoses extracted from the files was good for the majority of outcomes of interest it was fair in terms of hypertension (κ = 0.38).

Conclusion: This study supports observations suggesting a potential link between a lack of CL at conception and adverse maternal and neonatal outcomes. Further investigations on causes and pathophysiological relationships are yet to be conducted.

Natural vs. programmed cycles for frozen embryo transfer: study protocol for an investigator-initiated, randomized, controlled, multicenter clinical trial

Background

Randomized trials of assisted reproductive technology (ART) have been designed for outcomes of clinical pregnancy or live birth and have not been powered for obstetric outcomes such as preeclampsia, critical for maternal and fetal health. ART increasingly involves frozen embryo transfer (FET). Although there are advantages of FET, multiple studies have shown that risk of preeclampsia is increased with FET compared with fresh embryo transfer, and the reason for this difference is not clear. NatPro will compare the proportion of preeclampsia between two commonly used protocols for FET,modified natural and programmed cycle.

Methods

In this two-arm, parallel-group, multi-center randomized trial, NatPro will randomize 788 women to either modified natural or programmed FET and follow them for up to three FET cycles. Primary outcome will be the proportion of preeclampsia in women with a viable pregnancy assigned to a modified natural cycle FET (corpus luteum present) protocol compared to the proportion of preeclampsia in pregnant women assigned to a programmed FET (corpus luteum absent) protocol. Secondary outcomes will compare the proportion of live births and the proportion of preeclampsia with severe features between the protocols.

Conclusion

This study has a potential significant impact on millions of women who pursue ART to build their families. NatPro is designed to provide clinically relevant guidance to inform patients and clinicians regarding maternal risk with programmed and modified natural cycle FET protocols. This study will also provide accurate point estimates regarding the likelihood of live birth with programmed and modified natural cycle FET.

Trial registration

ClinicalTrials.govNCT04551807. Registered on September 16, 2020

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05637-3.

Do frozen embryo transfers modify the epigenetic control of imprinted genes and transposable elements in newborns compared with fresh embryo transfers and natural conceptions?

OBJECTIVE

To determine whether the epigenetic control of imprinted genes (IGs) and transposable elements (TEs) differs at birth between fresh or frozen embryo transfers and natural conceptions.

DESIGN

Prospective study.

SETTING

University hospital.

PATIENT(S)

A total of 202 singleton births were divided into three groups: 84 natural pregnancies (controls), 66 in vitro fertilization/intracytoplasmic sperm injection with fresh embryo transfers, and 52 vitro fertilization/intracytoplasmic sperm injection with frozen embryo transfers.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Pyrosequencing was used to assess the DNA methylation profiles of three IGs (H19/IGF2:IG-DMR [two sequences], KCNQ1OT1:TSS-DMR, and SNURF:TSS-DMR) and two TEs (LINE-1 and HERV-FRD) in cord blood and placenta. The quantitative reverse transcriptase polymerase chain reaction was used to study the transcription of three IGs (H19, KCNQ1, and SNRPN) and two TEs (LINE-1 and ORF2).

RESULT(S)

After adjustment, the placental DNA methylation levels of H19/IGF2 were lower in the fresh embryo transfer group than in the control (H19/IGF2-seq1) and frozen embryo transfer (H19/IGF2-seq2) groups. The DNA methylation rate for LINE-1 was lower in placentas from the fresh embryo transfer group than in placentas from the control and frozen embryo transfer groups and for HERV-FRD compared with controls. In cord blood, DNA methylation levels were not significantly associated with the mode of conception. The relative expression of LINE-1 and ORF2 was decreased in both cord blood and placental tissues from fresh embryo transfer conceptions compared with natural conceptions and frozen embryo transfer conceptions.

CONCLUSION(S)

Compared with natural conceptions and frozen embryo transfers, fresh embryo transfers were associated with methylation and/or transcription changes in some TEs and IGs, mostly in placental samples, which could indicate altered placental epigenetic regulation resulting from ovarian stimulation protocols.

Age-specific effect of fresh versus frozen embryo transfer on fetal anomalies or intrauterine growth restriction rate

OBJECTIVE

To compare the prevalence of congenital fetal anomalies or intrauterine fetal growth restriction (IUGR) diagnosed prenatally between two in-vitro fertilization (IVF) methods-fresh embryo transfer (ET) and frozen embryo transfer (FET).

MATERIALS AND METHODS

We retrospectively reviewed medical records of patients that had conceived via IVF, and had a fetal anatomical scan performed at Taiji Clinic between 2015 and 2019. The prevalence of fetal anomalies or IUGR between both IVF methods were compared. Prevalence of congenital anomalies or IUGR by maternal age and embryo transfer type were compared by means of Chi-square analysis. Using multivariate logistic regression, we investigated factors that might be associated with higher rates of fetal anomalies or IUGR, such as parity and number of embryos transferred.

RESULTS

A total of 2441 cases were selected (ET: n = 627 and FET: n = 1814). There was non-significant difference in the prevalence of fetal anomalies or IUGR between ET and FET groups (6.4% vs. 5.5%, p = 0.39). However, among women younger than 34 years of age, prevalence of fetal anomalies or IUGR was significantly higher in ET group (4.6% vs. 9.9%, p = 0.03).

CONCLUSIONS

Our findings suggest an age-specific effect of IVF method on the rate of fetal anomalies or IUGR and may provide useful information for physicians and infertile couples to optimize their IVF treatment plans and improve birth outcomes.

Childhood growth of term singletons born after frozen compared with fresh embryo transfer

RESEARCH QUESTION

Is the growth of term singletons born after frozen embryo transfer (FET) comparable to those born after fresh embryo transfer and natural conception up to 5 years of age?

DESIGN

Observational cohort study in an academic medical centre and municipal child health clinics with repeated measurements carried out by medical professionals. Term singletons born after FET (n = 110) and fresh embryo transfer (n = 181) and their matched natural conception controls (n = 543) born in Oulu, Northern Finland, were included. Mean weights, lengths, heights and head circumferences at the ages of 4, 8 and 18 months and 3 and 5 years were compared. At 3 and 5 years, body mass indices were compared.

RESULTS

Childhood growth did not differ between term singletons born after FET, fresh embryo transfer and natural conception, correcting for exact age at measurement and adjusting for maternal body mass index and paternal height.

CONCLUSIONS

Similar growth between children born after FET, fresh embryo transfer and natural conception offers reassurance of the safety and feasibility of the steadily increasing use of embryo cryopreservation in assisted reproduction.

Analysis of Delivery in Singleton Pregnancies Achieved by In Vitro Fertilization

BACKGROUND: Birth after IVF is increasingly observed in modern obstetrics, so knowledge of its features is of paramount importance for clinical practice.  AIM: The purpose of our study was to compare IVF and spontaneous singleton pregnancies in terms of cesarean section rate, operative vaginal birth rate, induction of labor, manual removal of the placenta in vaginal births, severe PPH and need for blood transfusion after delivery.   MATERIAL AND METHODS: We conducted a retrospective study at "Maichin Dom" University Hospital in Sofia, Bulgaria for the period from January 2013 to December 2017 and analyzed 402 singleton IVF pregnancies and compared them with 523 spontaneous singleton pregnancies    RESULTS: We found a significantly higher rate of cesarean sections in IVF compared to spontaneous pregnancies [OR 1.73; 95% CI 1.4-2.14; p<0.001]. Vaginal delivery after IVF is associated with a higher incidence of operative vaginal delivery than spontaneous pregnancies [OR 2.27; 95% CI 1.14 - 4.52; p=0.018]. No statistical differences in rates of labor induction and manual removal of the placenta between two groups were estimated (p>0.05). Severe PPH and blood transfusions were three times higher in patients after IVF undergoing a cesarean section than in those with spontaneous singleton pregnancies [OR 3.0; 95% CI 1.11 - 8.11; p=0.018].   CONCLUSION: IVF singleton pregnancies are associated with a higher risk of cesarean section as well as some obstetric complications. Obstetricians should treat these pregnancies with caution in order to reduce cesarean section rate and improve the outcome.

Cardiac remodeling in fetuses conceived by ARTs: fresh versus frozen embryo transfer

STUDY QUESTION

Do fetuses from frozen embryo transfer (FET) present signs of cardiac remodeling and suboptimal function similar to those observed in fetuses from fresh embryo transfer (ET)?

SUMMARY ANSWER

Fetuses from both fresh ET and FET present signs of fetal cardiac remodeling and suboptimal function, with more pronounced changes after fresh ET as compared to FET.

WHAT IS KNOWN ALREADY

Our group and others have previously demonstrated that fetuses and children conceived by ARTs present cardiac remodeling and suboptimal function. These fetuses show dilated atria, more globular and thicker ventricles, reduced longitudinal motion, and impaired relaxation. Cardiac changes were already present in utero and persisted after birth. Most of the ART fetuses included in previous publications were from fresh ET. However, singletons from FET have different perinatal outcomes compared to those from fresh ET. There are no previous studies comparing cardiac morphology and function between fetuses following fresh and FET.

STUDY DESIGN, SIZE, DURATION

This is a prospective cohort study of 300 singleton pregnancies recruited from 2017 to 2020, including 100 spontaneously conceived (SC) pregnancies, 100 fetuses conceived by IVF with FET, and 100 fetuses conceived by IVF with fresh ET. Fetal structural and functional echocardiography was performed in all pregnancies.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Pregnancies conceived by IVF were recruited from a single assisted reproduction center, ensuring homogeneity in IVF stimulation protocols, endometrial preparation for FET, laboratory procedures, and embryo culture conditions. SC pregnancies from fertile couples were selected from the general population and matched to IVF pregnancies by maternal age. Epidemiological and perinatal outcomes were collected in all cases. Fetal echocardiography was performed at 28-33 weeks of pregnancy to assess cardiac structure and function in all pregnancies. All echocardiographic comparisons were adjusted by maternal age, nulliparity, birthweight centile, preeclampsia, and prematurity.

MAIN RESULTS AND THE ROLE OF CHANCE

Parental age, ethnicity, body mass index and smoking were similar among the study groups. Median gestational age at echocardiography and estimated fetal weight were similar in all study groups. Both fresh ET and FET groups showed similar fetal echocardiographic changes, with more pronounced features in the fresh ET as compared to FET pregnancies. Fetuses conceived by IVF showed larger atria (right atria-to-heart ratio: fresh ET mean 18.1% (SD 3.2) vs FET 18.0% (3.9) vs SC 17.3% (3.2); linear tendency P-value <0.001), more globular ventricles (right ventricular sphericity index: fresh ET 1.62 (0.29) vs FET 1.61 (0.25) vs SC 1.68 (0.26); <0.001) and thicker myocardial walls (relative wall thickness: fresh ET 0.79 (0.21) vs FET 0.74 (0.22) vs SC 0.65 (0.25); <0.001) as compared to SC pregnancies. Both fresh ET and FET groups also had signs of suboptimal systolic and diastolic function, with reduced tricuspid annular systolic peak velocity (fresh ET 7.17 cm/s (1.22) vs FET 7.41 cm/s (1.19) vs SC 7.58 cm/s (1.32); <0.001) and increased left myocardial performance index (fresh ET 0.53 (0.08) vs FET 0.53 (0.08) vs SC 0.50 (0.09); <0.001) as compared to SC pregnancies.

LIMITATIONS, REASONS FOR CAUTION

The cardiac changes reported here are subclinical, with most cardiovascular indexes lying within normal ranges. Although echocardiographic changes are recognized as potential cardiovascular risk factors, their association with the long-term cardiovascular disease remains to be proven. The observed milder fetal cardiac features in FET fetuses cannot condition the choice of this technique and must be considered together with the global perinatal results related to these gestations.

WIDER IMPLICATIONS OF THE FINDINGS

The identification of cardiac remodeling in fetuses conceived by IVF with fresh ET and FET represents an opportunity for early detection. Future studies are warranted to study the potential long-term consequences of these findings.

STUDY FUNDING/COMPETING INTEREST(S)

This project has been partially funded with support from the Erasmus + Programme of the European Union (Framework Agreement number: 2013-0040). This publication reflects the views only of the author, and the Commission cannot be held responsible for any use, which may be made of the information contained therein. Additionally, the research leading to these results has received funding from 'la Caixa' Foundation under grant agreement LCF/PR/GN18/10310003, the Instituto de Salud Carlos III (PI15/00130, PI17/00675, PI18/00073) integrated into the Plan Nacional de I + D+I and cofinanced by ISCIII-Subdirección General de Evaluación and Fondo Europeo de Desarrollo Regional (FEDER) 'Una manera de hacer Europa', Cerebra Foundation for the Brain Injured Child (Carmarthen, Wales, UK) and AGAUR 2017 SGR grant n° 1531. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Letrozole-induced frozen embryo transfer cycles are associated with a lower risk of hypertensive disorders of pregnancy among women with polycystic ovary syndrome

BACKGROUND

Observational retrospective data suggest that an artificial cycle frozen embryo transfer may be associated with a higher risk of hypertensive disorder of pregnancy than a natural cycle frozen embryo transfer among women with regular ovulatory cycles. The corpus luteum, which is not present in the artificial frozen cycles, is at least partly responsible for this poor obstetrical outcome. However, an artificial cycle is the most frequently used regimen for women with polycystic ovary syndrome undergoing frozen embryo transfer. Whether the risk of hypertensive disorder of pregnancy could be mitigated by employing physiological frozen embryo transfer protocols that lead to the development of a corpus luteum in patients with polycystic ovary syndrome remains unknown.

OBJECTIVE

This study aimed to investigate the impact of letrozole use during frozen embryo transfer cycles on obstetrical and perinatal outcomes of singleton and twin pregnancies compared with artificial frozen cycles among women with polycystic ovary syndrome.

STUDY DESIGN

This retrospective cohort study involved women with polycystic ovary syndrome who had undergone artificial frozen cycles or letrozole-stimulated frozen cycles during the period from 2010 to 2018 at a tertiary care center. The primary outcome was the incidence of hypertensive disorder of pregnancy. A multivariable logistic regression analysis was performed to control for the relevant confounders.

RESULTS

A total of 2427 women with polycystic ovary syndrome were included in the final analysis. Of these women, 1168 underwent artificial cycles and 1259 underwent letrozole treatment, of which 25% of women treated with letrozole alone and 75% of women receiving letrozole combined with gonadotropins. After controlling for maternal characteristics and treatment variables, no significant difference was noticed regarding gestational diabetes mellitus, abnormal placentation, and preterm premature rupture of membranes between groups in both singleton and twin pregnancies. For birth outcomes, the prevalence rates of preterm birth, perinatal death, and birthweight outcomes were all comparable between groups in both singletons and twins. However, singleton pregnancies resulting from letrozole-stimulated cycles had a lower risk of hypertensive disorder of pregnancy than those conceived by artificial cycles (adjusted odds ratio, 0.63; 95% confidence interval, 0.40-0.98). Furthermore, a decreased risk of hypertensive disorder of pregnancy was seen among women with twin deliveries resulting from letrozole-stimulated cycles vs artificial cycles (adjusted odds ratio, 0.52; 95% confidence interval, 0.30-0.87). In addition, the cesarean delivery rate was significantly lower for singletons but not for twins in the letrozole group compared with pregnancies from the artificial cycle group (adjusted odds ratio, 0.63; 95% confidence interval, 0.50-0.78, and adjusted odds ratio, 1.20; 95% confidence interval, 0.65-2.23, respectively).

CONCLUSION

In women with polycystic ovary syndrome undergoing frozen embryo transfer, letrozole use for endometrial preparation was associated with a lower risk of hypertensive disorder of pregnancy than artificial cycles for endometrial preparation. Our findings provided a foundation that the increased risk of hypertensive disorder of pregnancy associated with frozen embryo transfer might be mitigated by utilizing physiological endometrial preparation protocols that lead to the development of a corpus luteum, such as a mild ovarian stimulation cycle for oligo- or anovulatory women.

Higher estradiol levels are associated with lower neonatal birthweight after fresh and frozen embryo transfers. A cohort study of 3631 singleton IVF pregnancies

AIM

To assess the birthweight of neonates conceived after fresh and frozen embryo transfers (FET) and, if different, to investigate whether estradiol levels during the late follicular phase were associated with the observed difference.

METHODS

Singleton pregnancies from fresh and FET transfers between January 1990 and December 2013 were compared retrospectively. A total of 2885 singleton pregnancies after fresh embryo transfer and 746 after FET were analyzed. Obstetric and neonatal outcomes were compared between fresh and FET cycles.

RESULTS

The singletons born after FET were found to have a significantly higher birth weight (3313 g), compared to those born after fresh embryo transfer (3143 g); p < .001. The main predictor of this difference was found to be estradiol levels at the end of the follicular phase. The difference in birthweight was inversely correlated to estradiol levels considering all cycles together but also considering fresh and frozen cycles separately.

CONCLUSIONS

Our study demonstrates a link between high estradiol levels and low birth weight of singletons after IVF both in fresh and frozen-thawed embryo transfer cycles. It provides additional support to the involvement of hyperestrogenemia in the process of implantation and on the subsequent fetal development.

Assisted reproductive technology and hypertensive disorders of pregnancy: systematic review and meta-analyses

Background

Hypertensive disorders of pregnancy (HDP) is one of the most common pregnancy complications and causes of maternal morbidity and mortality. Assisted reproductive technology (ART) has been associated with adverse pregnancy outcomes, including HDP. However, the impact of multiple pregnancies, oocyte donation, as well as fresh and frozen embryo transfer needs to be further studied. We conducted a systematic review and meta-analyses to evaluate the association between ART and HDP or preeclampsia relative to spontaneous conception (SC).

Methods

We identified studies from EMBASE, MEDLINE, and Cochrane Library (up to April 8, 2020) and manually using structured search strategies. Cohort studies that included pregnancies after in vitro fertilization (IVF) with or without intracytoplasmic sperm fertilization (ICSI) relative to SC with HDP or preeclampsia as the outcome of interest were included. The control group was women who conceived spontaneously without ART or fertility medications. The pooled results were reported in odds ratios (OR) with 95% confidence intervals based on random effects models. Numbers needed to harm (NNH) were calculated based on absolute risk differences between exposure and control groups.

Results

Eighty-five studies were included after a screening of 1879 abstracts and 283 full text articles. Compared to SC, IVF/ICSI singleton pregnancies (OR 1.70; 95% CI 1.60–1.80; I² = 80%) and multiple pregnancies (OR 1.34; 95% CI 1.20–1.50; I² = 76%) were both associated with higher odds of HDP. Singleton pregnancies with oocyte donation had the highest odds of HDP out of all groups analyzed (OR 4.42; 95% CI 3.00–6.51; I² = 83%). Frozen embryo transfer resulted in higher odds of HDP (OR 1.74; 95% CI 1.58–1.92; I² = 55%) than fresh embryo transfer (OR 1.43; 95% CI 1.33–1.53; I² = 72%). The associations between IVF/ICSI pregnancies and SC were similar for preeclampsia. Most interventions had an NNH of 40 to 100, while singleton and multiple oocyte donation pregnancies had particularly low NNH for HDP (16 and 10, respectively).

Conclusions

Our meta-analysis confirmed that IVF/ICSI pregnancies are at higher odds of HDP and preeclampsia than SC, irrespective of the plurality. The odds were especially high in frozen embryo transfer and oocyte donation pregnancies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03938-8.

Secretory products of the corpus luteum and preeclampsia

BACKGROUND

Despite significant advances in our understanding of the pathophysiology of preeclampsia (PE), there are still many unknowns and controversies in the field. Women undergoing frozen-thawed embryo transfer (FET) to a hormonally prepared endometrium have been found to have an unexpected increased risk of PE compared to women who receive embryos in a natural FET cycle. The differences in risk have been hypothesized to be related to the absence or presence of a functioning corpus luteum (CL).

OBJECTIVE AND RATIONALE

To evaluate the literature on secretory products of the CL that could be essential for a healthy pregnancy and could reduce the risk of PE in the setting of FET.

SEARCH METHODS

For this review, pertinent studies were searched in PubMed/Medline (updated June 2020) using common keywords applied in the field of assisted reproductive technologies, CL physiology and preeclampsia. We also screened the complete list of references in recent publications in English (both animal and human studies) on the topics investigated. Given the design of this work as a narrative review, no formal criteria for study selection or appraisal were utilized.

OUTCOMES

The CL is a major source of multiple factors regulating reproduction. Progesterone, estradiol, relaxin and vasoactive and angiogenic substances produced by the CL have important roles in regulating its functional lifespan and are also secreted into the circulation to act remotely during early stages of pregnancy. Beyond the known actions of progesterone and estradiol on the uterus in early pregnancy, their metabolites have angiogenic properties that may optimize implantation and placentation. Serum levels of relaxin are almost undetectable in pregnant women without a CL, which precludes some maternal cardiovascular and renal adaptations to early pregnancy. We suggest that an imbalance in steroid hormones and their metabolites and polypeptides influencing early physiologic processes such as decidualization, implantation, angiogenesis and maternal haemodynamics could contribute to the increased PE risk among women undergoing programmed FET cycles.

WIDER IMPLICATIONS

A better understanding of the critical roles of the secretory products of the CL during early pregnancy holds the promise of improving the efficacy and safety of ART based on programmed FET cycles.

High birth weight and large-for-gestational-age in singletons born after frozen compared to fresh embryo transfer, by gestational week: a Nordic register study from the CoNARTaS group

STUDY QUESTION

When do the differences in birth weights become apparent between singletons born after frozen embryo transfer (FET) and fresh embryo transfer (fresh ET)?

SUMMARY ANSWER

Mean birth weights after FET become significantly higher starting from gestational week (GW) 33 among boys and from GW 34 among girls.

WHAT IS KNOWN ALREADY

In recent years, there has been a steep rise in recorded FET treatments, enabling widespread use of elective single embryo transfer, thus reducing the risks associated with multiple gestations. However, singletons born after FET are heavier and there is a higher risk of large-for-gestational-age (LGA) (birth weight > 90 percentiles) compared to fresh ET. In contrast, risk of small-for-gestational-age (SGA, birth weight < 10 percentiles) is lower in singletons born after FET compared to fresh ET. The reasons, timing and consequences of these differences remain largely unclear. There is limited evidence about whether this difference in growth develops before the last trimester of pregnancy.

STUDY DESIGN, SIZE, DURATION

This retrospective Nordic register-based cohort study compared singletons born after FET (n = 17 500) to singletons born after fresh ET (n = 69 510) and natural conception (NC, n = 3 311 588). All live born singletons born between the years 2000 and 2015 in Denmark, Norway and Sweden at gestational age ≥22 weeks were included from the population-based Committee of Nordic ART and Safety (CoNARTaS) study population.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Children born after FET were compared to those born after fresh ET and NC for mean birth weight and proportion of LGA and SGA for each GW at birth. Chi-square test and tests for relative proportions were used to compare categorical variables and Student's t-test was used to compare continuous variables. Adjusted odds ratios (aORs) for LGA and SGA were calculated using logistic regressions, adjusting for year of birth, maternal age, parity, BMI, chronic hypertension, diabetes, smoking and offspring sex.

MAIN RESULTS AND THE ROLE OF CHANCE

Mean birth weights were significantly higher after FET compared to fresh ET starting from GW 33 (range from 75 g to 228 g by week) for boys and starting from GW 34 (range from 90 g to 236 g by week) for girls. Boys born after FET had a significantly higher proportion of LGA (11.0-15.1%) at birth between GW 36 and 42, compared to those born after fresh ET (7.1-9.4%) (range from P < 0.001 to P = 0.048 by week). For girls born after FET, the difference was seen between GW 37 and 42 (10.6-13.4%) compared to those born after fresh ET (6.6-8.0%) (range from P < 0.001 to P = 0.009 by week).The proportion of SGA was significantly lower among boys born after FET (7.6-8.7%) compared to fresh ET (11.9-13.6%) between GW 36 and 42 (range from P < 0.001 to P = 0.016 by week). For girls born after FET, the difference was seen between GW 38 and 42 (7.0-9.3%) compared to those born after fresh ET (13.0-14.6%) (P < 0.001). The proportion of LGA (12.3-15.1%) was significantly higher for boys born after FET between GW 38 and 41 (P < 0.001) and for girls born after FET (12.6-13.4%) between GW 37 and 40 (range from P < 0.001 to P = 0.018 by week), compared to naturally conceived boys (9.7-9.9%) and girls (9.0-10.0%). All singletons born after FET had a higher risk of LGA compared to singletons born after fresh ET (aOR 1.87, 95% CI 1.76-1.98) and singletons born after NC (aOR 1.28, 95% CI 1.22-1.35).

LIMITATIONS, REASONS FOR CAUTION

There may be residual confounding factors that we were not able to control for, most importantly the causes of preterm birth, which may also influence foetal growth. A further limitation is that we have no knowledge on growth patterns between implantation and GW 22. Finally, the number of children born extremely preterm or post-term was limited even in this large study population.

WIDER IMPLICATIONS OF THE FINDINGS

This is, to date, the largest study on birth weights among preterm and term ART singletons with a population-based design and NC control group. The results suggest that the freeze-thaw process is associated with higher birthweights and greater risk of LGA at least in the last trimester of pregnancy. This is an important aspect of the safety profile of ART. More research is needed on the long-term outcome of these children.

STUDY FUNDING/COMPETING INTEREST(S)

The CoNARTaS collaboration has received the following funding: the Nordic Trial Alliance: a pilot project jointly funded by the Nordic Council of Ministers and NordForsk [71450], the Central Norway Regional Health Authorities [46045000], the Norwegian Cancer Society [182356-2016], the Nordic Federation of Obstetrics and Gynaecology [NF13041, NF15058, NF16026 and NF17043], the Interreg Öresund-Kattegat-Skagerrak European Regional Development Fund (ReproUnion project) and the Research Council of Norway's Centre of Excellence funding scheme [262700]. None of the authors have any competing interests to declare.

TRIAL REGISTRATION NUMBER

ISRCTN11780826.

When Should We Freeze Embryos? Current Data for Fresh and Frozen Embryo Replacement IVF Cycles

Recent years have seen a dramatic rise in the number of frozen-thawed embryo replacement (FER) cycles. Along with the advances in embryo cryopreservation techniques, the optimization of endometrial receptivity has resulted in outcomes for FER that are similar to fresh embryo transfer. However, the question of whether the Freeze all strategy is for all is nowadays a hot topic. This review addresses this issue and describes current evidence based on randomized controlled trials and observational studies. To date, it is reasonable to perform FER in cases with a clear indication for the benefits of such strategy including impending ovarian hyperstimulation syndrome (OHSS) or preimplantation genetic testing for aneuploidy (PGT-A); however, this strategy does not fit for all. This review analyses the pros and cons of the freeze all strategy highlighting the need to follow a personalized plan in embryo transfer, avoiding a freeze all methodology for all patients in an unselected manner.

Impact of trophectoderm biopsy on obstetric and perinatal outcomes following frozen-thawed embryo transfer cycles

STUDY QUESTION

Does trophectoderm biopsy for preimplantation genetic testing (PGT) increase the risk of obstetric or perinatal complications in frozen-thawed embryo transfer (FET) cycles?

SUMMARY ANSWER

Trophectoderm biopsy may increase the risk of hypertensive disorders of pregnancy (HDP) in pregnancies following FET cycles.

WHAT IS KNOWN ALREADY

Trophectoderm biopsy has replaced blastomere biopsy as the standard of care to procure cells for PGT analysis. Recently, there has been concern that trophectoderm biopsy may adversely impact obstetric and perinatal outcomes. Previous studies examining this question are limited by use of inappropriate control groups, small sample size or reporting on data that no longer reflects current IVF practice.

STUDY DESIGN, SIZE, DURATION

This was a retrospective cohort study conducted at a single university-affiliated fertility center. A total of 756 patients who underwent FET with transfer of previously vitrified blastocysts that had either trophectoderm biopsy or were unbiopsied and resulted in a singleton live birth between 2013 and 2019 were included.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Obstetric and perinatal outcomes for patients aged 20-44 years who underwent FET with transfer of previously vitrified blastocysts that were either biopsied (n = 241) or unbiopsied (n = 515) were analyzed. Primary outcome was odds of placentation disorders including HDP and rate of fetal growth restriction (FGR). Binary logistic regression was performed to control for potential covariates.

MAIN RESULTS AND THE ROLE OF CHANCE

The biopsy group was significantly older, had fewer anovulatory patients, was more often nulliparous and had fewer embryos transferred compared to the unbiopsied group. After controlling for potential covariates, the probability of developing HDP was significantly higher in the biopsy group compared with unbiopsied group (adjusted odds ratio (aOR) 1.943, 95% CI 1.072-3.521; P = 0.029).There was no significant difference between groups in the probability of placenta previa or placenta accreta. There was also no significant difference in the rate of FGR (aOR 1.397; 95% CI, 0.815-2.395; P = 0.224) or the proportion of low (aOR 0.603; 95% CI, 0.336-1.084; P = 0.091) or very low (aOR 2.948; 95% CI, 0.613-14.177; P = 0.177) birthweight infants comparing biopsied to unbiopsied groups.

LIMITATIONS, REASON FOR CAUTION

This was a retrospective study performed at a single fertility center, which may limit the generalizability of our findings.

WIDER IMPLICATIONS OF THE FINDINGS

Trophectoderm biopsy may increase the risk of HDP in FET cycles, however, a prospective multicenter randomized trial should be performed to confirm these findings.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was obtained for this study. The authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

NA.

Frozen Embryo Transfer and Preeclampsia Risk

Worldwide, the use of Assisted Reproductive Technology (ART) has been steadily rising over recent years. With the continuous improvements in cryopreservation techniques and the growing practice of single embryo transfer, the proportion of frozen embryo transfer (FET) cycles has been increasing, therefore raising concern about the safety of this ART technique to both mothers and infants. This review aims to summarize the current evidence regarding the risk of preeclampsia in singleton pregnancies achieved by autologous FET compared to fresh embryo transfer, and to discuss the influence of different protocols used for endometrium preparation in frozen cycles on the risk of this obstetric complication. Several studies have reported a higher risk of hypertensive disorders, including preeclampsia, in pregnancies following FET compared with fresh embryo transfer. Recently, artificial FET cycles, which preclude the development of a corpus luteum, were shown to be associated with an increased preeclampsia risk in comparison with natural and stimulated cycles. Importantly, no difference was found between FET in a modified natural cycle and spontaneous conception. It has been proposed that the absence of the corpus luteum in artificial cycles may, at least partly, contribute to the observed increased risk of preeclampsia. Indeed, the corpus luteum secretes vasoactive hormones, such as relaxin, which are not replaced in artificial cycles, thereby compromising maternal cardiovascular adaptations to pregnancy, resulting in an increased risk of preeclampsia. If these findings are confirmed by a randomized controlled trial, natural, modified natural or stimulated cycles might be preferred over artificial cycles in eligible patients.

Effect of parental and ART treatment characteristics on perinatal outcomes

STUDY QUESTION

Do parental characteristics and treatment with ART affect perinatal outcomes in singleton pregnancies?

SUMMARY ANSWER

Both parental and ART treatment characteristics affect perinatal outcomes in singleton pregnancies.

WHAT IS KNOWN ALREADY

Previous studies have shown that singleton pregnancies resulting from ART are at risk of preterm birth. ART children are lighter at birth after correction for duration of gestation and at increased risk of congenital abnormalities compared to naturally conceived children. This association is confounded by parental characteristics that are also known to affect perinatal outcomes. It is unclear to which extent parental and ART treatment characteristics independently affect perinatal outcomes.

STUDY DESIGN, SIZE, DURATION

All IVF clinics in the Netherlands (n = 13) were requested to provide data on all ART treatment cycles (IVF, ICSI and frozen-thawed embryo transfers (FET)), performed between 1 January 2000, and 1 January 2011, which resulted in a pregnancy. Using probabilistic data-linkage, these data (n = 36 683) were linked to the Dutch Perinatal Registry (Perined), which includes all children born in the Netherlands in the same time period (n = 2 548 977).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Analyses were limited to singleton pregnancies that resulted from IVF, ICSI or FET cycles. Multivariable models for linear and logistic regression were fitted including parental characteristics as well as ART treatment characteristics. Analyses were performed separately for fresh cycles and for fresh and FET cycles combined. We assessed the impact on the following perinatal outcomes: birth weight, preterm birth below 37 or 32 weeks of gestation, congenital malformations and perinatal mortality.

MAIN RESULTS AND THE ROLE OF CHANCE

The perinatal outcomes of 31 184 out of the 36 683 ART treatment cycles leading to a pregnancy were retrieved through linkage with the Perined (85% linkage). Of those, 23 671 concerned singleton pregnancies resulting from IVF, ICSI or FET. Birth weight was independently associated with both parental and ART treatment characteristics. Characteristics associated with lower birth weight included maternal hypertensive disease, non-Dutch maternal ethnicity, nulliparity, increasing duration of subfertility, hCG for luteal phase support (compared to progesterone), shorter embryo culture duration, increasing number of oocytes retrieved and fresh embryo transfer. The parental characteristic with the greatest effect size on birth weight was maternal diabetes (adjusted difference 283 g, 95% CI 228-338). FET was the ART treatment characteristic with the greatest effect size on birth weight (adjusted difference 100 g, 95% CI 84-117) compared to fresh embryo transfer. Preterm birth was more common among mothers of South-Asian ethnicity. Preterm birth was less common among multiparous women and women with 'male factor' as treatment indication (compared to 'tubal factor').

LIMITATIONS, REASONS FOR CAUTION

Due to the retrospective nature of our study, we cannot prove causality. Further limitations of our study were the inability to adjust for mothers giving birth more than once in our dataset, missing values for several variables and limited information on parental lifestyle and general health.

WIDER IMPLICATIONS OF THE FINDINGS

Multiple parental and ART treatment characteristics affect perinatal outcomes, with birth weight being influenced by the widest range of factors. This highlights the importance of assessing both parental and ART treatment characteristics in studies that focus on the health of ART-offspring, with the purpose of modifying these factors where possible. Our results further support the hypothesis that the embryo is sensitive to its early environment.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by Foreest Medical School, Alkmaar, the Netherlands (grants: FIO 1307 and FIO 1505). B.W.M. reports grants from NHMRC and consultancy for ObsEva, Merck KGaA, iGenomics and Guerbet. F.B. reports research support grants from Merck Serono and personal fees from Merck Serono. A.C. reports travel support from Ferring BV. and Theramex BV. and personal fees from UpToDate (Hyperthecosis), all outside the remit of the current work. The remaining authors report no conflict of interests.

TRIAL REGISTRATION NUMBER

N/A.

Supraphysiological estradiol levels on the hCG trigger day are associated with SGA for singletons born from fresh embryo transfer

The effects of supraphysiological estradiol (E2) on neonatal outcomes and the significance of specific E2 concentrations remain unclear. The purpose of this study was to investigate whether supraphysiological E2 levels on the human chorionic gonadotropin (hCG) trigger day are associated with small size for gestational age (SGA) in singletons born from fresh embryo transfer (ET) cycles. Patients with singleton pregnancies who delivered after the transfer of fresh embryos, during the period from July 2012 to December 2017, at our center were included. We excluded cycles involving a vanishing twin, maternal age >35 years, basal follicle-stimulating hormone ≥10 mIU/ml, or anti-Müllerian hormone ≤1 ng/ml. We then divided all cycles into five groups by E2 level on trigger day: group A, <2000 pg/ml (reference group); group B, 2000 pg/ml≤E2<2999 pg/ml; group C, 3000 pg/ml≤E2<3999 pg/ml; group D, 4000 pg/ml≤E2<4999 pg/ml; and group E, ≥5000 pg/ml. The prevalence of SGA among singletons from fresh ET was the primary outcome. The SGA rate significantly increased when the E2 level was ≥4000 pg/ml, as observed by comparing groups D (odds ratio [OR]: 1·79, 95% confidence interval [CI]: 1·16-2·76, P = 0·01) and E (OR: 1·68, 95% CI: 1·10-2·56, P = 0·02) with the reference group. Multivariate logistic regression indicated that a serum E2 level of at least 4000 pg/ml on the hCG trigger day was associated with increased SGA and with significant differences for groups D (adjusted OR [AOR]: 1·65, 95% CI: 1·05-2·59, P = 0·03) and E (AOR: 1·60, 95% CI: 1·03-2·53, P = 0·04) relative to the reference group. In conclusion, in fresh ET cycles, the supraphysiological E2 ≥4000 pg/ml on the hCG trigger day increases the risk of SGA.

Further evidence that a supraphysiologic estradiol level during ovarian stimulation affects birthweight: findings of fresh and frozen embryo transfer with comparable estradiol levels on human chorionic gonadotropin trigger

Studies have reported a supraphysiologic estradiol (E2) level during ovarian stimulation may be related to low birthweight after fresh embryo transfer (ET), but whether a high E2 level in the stimulation cycle affects birthweight via frozen ET remained controversial. The study was to investigate whether a supraphysiologic E2 level in ovarian stimulation cycle affects birth weight in infants conceived via subsequent FET. In this retrospective cohort study, 2525 singletons conceived via FET and 2668 singletons conceived via fresh ET were analyzed. The birthweight and incidences of small for gestational age (SGA) in infants conceived via FET in groups with low and high levels of E2 did not differ significantly. Multivariate analyses showed that the peak E2 level was not predictive of SGA in infants conceived via FET. Singletons conceived via fresh ET had a higher risk of SGA than those conceived via FET even after comparable previous exposure to a high level of E2 > 3000 pg/mL. Our study results indicated that the increased risk of SGA was at least partly a result of the supraphysiologic E2 exposure to the intrauterine environment.

Effect of pre-pregnancy body mass index on neonatal outcomes in women undergoing autologous frozen-thawed embryo transfer

OBJECTIVE

To investigate the associations between pre-pregnancy body mass index (BMI) and neonatal outcomes in women undergoing autologous frozen-thawed embryo transfer (FET).

DESIGN

Retrospective cohort study.

SETTING(S)

University-affiliated reproductive medical center.

PATIENT(S)

A total of 16,240 women with singleton deliveries achieved by autologous FET.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Neonatal outcomes included preterm birth (PTB), low birth weight (LBW), small-for-gestational age (SGA), large-for-gestational age (LGA), fetal macrosomia, and birth defects.

RESULT(S)

After adjusting for confounding factors, our study showed that in autologous FET cycles, the overweight women (23 kg/m²≤ BMI <27.5 kg/m²) were associated with increased rates of PTB (adjusted odds ratio [aOR], 1.226; 95% confidence interval [CI], 1.060-1.418), macrosomia (aOR, 1.692; 95% CI, 1.491-1.921), and LGA (aOR, 1.980; 95% CI, 1.715-2.286); and the obese women (BMI ≥27.5 kg/m²) were significantly associated with increased PTB (aOR, 1.503; 95% CI, 1.167-1.936), early PTB (aOR, 2.829; 95% CI, 1.679-4.765), very LBW (aOR, 3.087; 95% CI, 1.720-5.542), macrosomia (aOR, 2.325; 95% CI, 1.862-2.904), and LGA (aOR, 3.235; 95% CI, 2.561-4.085). The rate of SGA infants was higher in the underweight women (BMI <18.5 kg/m²) (aOR, 1.687; 95% CI, 1.375-2.071) than that in the normal-weight women (18.5 kg/m²≤ BMI ≤23 kg/m²). No significant difference was observed in the risk of birth defects between normal-weight cases and other BMI categories.

CONCLUSION(S)

Among women undergoing FET, pre-pregnancy BMI affected neonatal outcomes of singletons. BMI in Asian categories for overweight and obese showed significant increases in PTB, macrosomia, and LGA; early PTB and very LBW only increased in obese cases. In addition, underweight status was associated with increased risk of SGA. In contrast, there was no association between pre-pregnancy BMI and birth defects in FET cycles.

A systematic review of clinical efficacy of frozen-thawed embryos and fresh embryos in in-vitro fertilization cycles

BACKGROUND

Frozen-thawed embryo (FTE) and fresh embryo (FE) transfer are two common strategies in vitro fertilization (IVF), while the results and findings still vary among studies.

METHODS

We searched multiple databases for relevant studies comparing the clinical effects of FTE and FE. Meta-analyses were conducted with Review Manager 5.0 to assess the efficacy among included articles. We also analyzed the risk of bias for the reports.

RESULTS

Nine studies eventually met the inclusion criteria from 2010 to 2018, and 11396 patients were included. The meta-analyses indicated no significant difference in biochemical pregnancy, clinical pregnancy and ongoing pregnancy rates. Meanwhile, the implantation rate and live birth rate in frozen-thawed embryos were much higher than those of fresh embryo. The birth weight in the frozen-thawed ET group was greater than that of the FE group, and the low birth weight rate in FTE was lower than FE group.

CONCLUSION

Our findings suggested a trend toward favouring frozen-thawed FTE might be a preferred transfer strategy for patients with IVF.

Influence of Placental Abnormalities and Pregnancy-Induced Hypertension in Prematurity Associated with Various Assisted Reproductive Technology Techniques

OBJECTIVE

Assisted reproductive technology (ART)-treated women exhibit increased risk of premature delivery compared to fertile women. We evaluated whether ART treatment modalities increase prematurity and whether placental abnormalities and pregnancy-induced hypertensive (PIH) disorders mediate these risks.

METHOD(S)

This retrospective study of ART-treated and fertile deliveries (2004-2017) used an ART-cycle database linked to Massachusetts birth certificates and hospital discharges. Outcomes of late preterm birth (LPTB: 34-36 weeks gestation) and early preterm birth (EPTB: <34 weeks gestation) were compared with term deliveries (≥37 weeks gestation) in ART-treated (linked to the ART database) and fertile (no indicators of infertility or ART) deliveries. ART treatments with autologous oocyte, donor oocyte, fresh or frozen embryo transfer (FET), intracytoplasmic sperm injection (ICSI) and no-ICSI were separately compared to the fertile group. Adjusted odds ratios (AOR) were calculated with multivariable logistic regression: placental abnormalities or PIH were quantified in the pathway as mediators.

RESULTS

There were 218,320 deliveries: 204,438 fertile and 13,882 ART-treated. All treatment types increased prematurity (AOR 1.31-1.58, LPTB; AOR 1.34-1.48, EPTB). Placental abnormalities mediated in approximately 22% and 38% of the association with LPTB and EPTB, respectively. PIH mediated 25% and 33% of the association with LPTB and EPTB in FET and donor oocyte cycles, more than other treatments (<10% LPTB and <13% EPTB).

CONCLUSIONS

ART-treatment and all ART modalities increased LPTB and EPTB when compared with fertile deliveries. Placental abnormalities modestly mediated associations approximately equally, while PIH was a stronger mediator in FET and donor oocyte cycles. Reasons for differences require exploration.

Caesarean section in pregnancies conceived by assisted reproductive technology: a systematic review and meta-analysis

Background

Caesarean section rates are higher among pregnancies conceived by assisted reproductive technology (ART) compared to spontaneous conceptions (SC), implying an increase in neonatal and maternal morbidity. We aimed to compare caesarean section rates in ART pregnancies versus SC, overall, by indication (elective versus emergent), and by type of ART treatment (in-vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), fresh embryo transfer, frozen embryo transfer) in a systematic review and meta-analysis.

Methods

We searched Medline, EMBASE and CINAHL databases using the OVID Platform from 1993 to 2019, and the search was completed in January 2020. The eligibility criteria were cohort studies with singleton conceptions after in-vitro fertilization and/or intracytoplasmic sperm injection using autologous oocytes versus spontaneous conceptions. The study quality was assessed using the Newcastle Ottawa Scale and GRADE approach. Meta-analyses were performed using odds ratios (OR) with a 95% confidence interval (CI) using random effect models in RevMan 5.3, and I-squared (I²) test > 75% was considered as high heterogeneity.

Results

One thousand seven hundred fifty studies were identified from the search of which 34 met the inclusion criteria. Compared to spontaneous conceptions, IVF/ICSI pregnancies were associated with a 1.90-fold increase of odds of caesarean section (95% CI 1.76, 2.06). When stratified by indication, IVF/ICSI pregnancies were associated with a 1.91-fold increase of odds of elective caesarean section (95% CI 1.37, 2.67) and 1.38-fold increase of odds of emergent caesarean section (95% CI 1.09, 1.75). The heterogeneity of the studies was high and the GRADE assessment moderate to low, which can be explained by the observational design of the included studies.

Conclusions

The odds of delivering by caesarean section are greater for ART singleton pregnancies compared to spontaneous conceptions. Preconception and pregnancy care plans should focus on minimizing the risks that may lead to emergency caesarean sections and finding strategies to understand and decrease the rate of elective caesarean sections.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03711-x.

Anesthetic Considerations for Cesarean Delivery After Uterine Transplant

Infertility has many etiologies and can have devastating consequences for young couples attempting to bring children into the world. Uterine factor for infertility is related to either uterine agenesis (Mayer-Rokitansky-Küster-Hauser [MRKH] syndrome), unexpected hysterectomy, or presence of a nonfunctioning uterus. In this review, a patient with MRKH syndrome underwent donor uterus transplantation at the Cleveland Clinic, conceived, and delivered the first healthy baby in the United States and the second worldwide. Additionally, we review the pertinent literature on anesthesia problems. Donor-related uterine transplant is a recent medical innovation requiring multidisciplinary expertise. In patients who deliver successfully, according to the current literature, the transplanted uterus can be used for one more pregnancy only if the mother so desires, otherwise cesarean hysterectomy (C-Hyst) should be performed. In the observed case, C-Hyst was performed because the patient developed placenta accreta and the couple desired no further pregnancy. In summary, with our limited data, careful management of these patients is required to ensure the best outcome for the mother and the newborn fetus.