Neonatal outcome of 937 children born after transfer of cryopreserved embryos obtained by ICSI and IVF and comparison with outcome data of fresh ICSI and IVF cycles

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.

Assisted reproduction and congenital malformations: A systematic review and meta-analysis

Prior studies have explored the links between congenital anomalies and assisted reproduction techniques, among other factors. However, it remains unclear whether a particular technique harbors an inherent risk of major congenital anomalies, either cumulatively or in an organ-specific manner. A meta-analysis was conducted using relevant studies from inception to February 2023 using six databases and two appropriate registers. Sources of heterogeneity were explored using sub-group analysis, using study weight, risk of bias and geographical location of original studies. Neonates conceived through assisted reproduction appear to have a higher risk of major congenital anomalies compared to naturally conceived neonates, OR 0.67 [95% CI 0.59, 0.76], I2 = 97%, p < 0.00001, with neonates conceived through intracytoplasmic sperm injection (ICSI) at a 9% higher chance of being affected in comparison to neonates conceived through in vitro fertilization (IVF). The increase in cardiac, gastrointestinal (GI), and neurological congenital anomalies appears to be independent of the assisted reproduction technique, while urogenital and musculoskeletal (MSK) anomalies were found to be increased in ICSI compared with IVF, OR 0.83 [95% CI 0.69, 0.98]; p = 0.03, I2 = 0%, and OR 0.65 [95% CI 0.49, 0.85]; p = 0.002, I2 = 80%, respectively. Neonates conceived using assisted reproduction techniques appear to be at higher risk of major congenital anomalies, with a higher risk attributable to conception using ICSI. The increase in cardiac, neurological, and GI congenital anomalies does not appear to be technique-specific, while the opposite held true for urogenital and MSK anomalies.

Children born to subfertile couples, how are they doing? Evidence from research

More than 10 million children have been born with assisted reproductive technology (ART) as we begin to enter the third generation of individuals conceived by ART. Here we summarise key messages from an enlarging body of literature regarding their health. Earlier research had pointed towards increases in perinatal, neonatal and neurological risks, such as preterm birth, low birth weight, congenital malformations and cerebral palsy. Many of these risks have continued to persist in most recent work but have shown reduction. Newer research proposes long-term cardiometabolic and endocrine concerns. Fortunately, most reports conclude there is little or no risk of increased childhood malignancy or abnormal neurodevelopment. Moving forward, new research may benefit from changes in comparator groups and a better understanding of infertility per se in ART, and the confounding role it probably plays in many of the known risk associations, to reliably scan the horizon for health threats for individuals born after ART.

Comparison of the perinatal outcomes of expected high ovarian response patients and normal ovarian response patients undergoing frozen-thawed embryo transfer in natural/small amount of HMG induced ovulation cycles

BACKGROUND

Due to the high risk of complications in fresh transfer cycles among expected high ovarian response patients, most choose frozen-thawed embryo transfer (FET). There are currently few researches on whether the FET outcomes of expected high ovarian response patients with regular menstrual cycles are similar to those of normal ovarian response. Therefore, our objective was to explore and compare pregnancy outcomes and maternal and neonatal outcomes of natural FET cycles between patients with expected high ovarian response and normal ovarian response with regular menstrual cycles based on the antral follicle count (AFC).

METHODS

This retrospective cohort study included 5082 women undergoing natural or small amount of HMG induced ovulation FET cycles at the Reproductive Center of the Third Affiliated Hospital of Zhengzhou University from January 1, 2017, to March 31, 2021. The population was divided into expected high ovarian response group and normal ovarian response group based on the AFC, and the differences in patient characteristics, clinical outcomes and perinatal outcomes between the two groups were compared.

RESULTS

Regarding clinical outcomes, compared with the normal ovarian response group, patients in the expected high ovarian response group had a higher clinical pregnancy rate (57.34% vs. 48.50%) and live birth rate (48.12% vs. 38.97%). There was no difference in the early miscarriage rate or twin pregnancy rate between the groups. Multivariate logistic regression analysis suggested that the clinical pregnancy rate (adjusted OR 1.190) and live birth rate (adjusted OR 1.171) of the expected high ovarian response group were higher than those of the normal ovarian response group. In terms of maternal and infant outcomes, the incidence of very preterm delivery in the normal ovarian response group was higher than that in the expected high ovarian response group (0.86% vs. 0.16%, adjusted OR 0.131), Other maternal and infant outcomes were not significantly different. After grouping by age (< 30 y, 30-34 y, 35-39 y), there was no difference in the incidence of very preterm delivery among the age subgroups.

CONCLUSION

For patients with expected high ovarian response and regular menstrual cycles undergoing natural or small amount of HMG induced ovulation FET cycles, the clinical and perinatal outcomes are reassuring. For patients undergoing natural or small amount of HMG induced ovulation FET cycles, as age increases, perinatal care should be strengthened during pregnancy to reduce the incidence of very preterm delivery.

Progesterone levels during ovarian stimulation in segmented ART cycles inversely correlate with normalized birthweight of neonates conceived through subsequent frozen-thawed embryo transfer

PURPOSE

To evaluate the association between serum progesterone (P) at the day of ovulation trigger and neonatal birthweight in singletons born after frozen-thawed embryo transfer in segmented ART cycles.

METHODS

A retrospective multicenter cohort study involving data from patients who achieved uncomplicated pregnancy and term delivery of ART-conceived singleton babies following a segmented GnRH antagonist cycle. The main outcome was birthweight's z-score of the neonate. Univariate and multivariate linear logistic regression analyses were made to investigate the relation of z-score with variables inherent to the patient and to the ovarian stimulation. The variable P per oocyte was created by dividing the value of progesterone at ovulation trigger by the number of oocytes retrieved at oocyte retrieval.

RESULTS

A total of 368 patients were included in the analysis. At univariate linear regression, the birthweight z-score of the neonate appeared to be inversely related to both P levels at the ovulation trigger (- 0.101, p = 0.015) and P levels per oocyte at trigger (- 1.417, p = 0.001), while it was directly related to the height of the mother (0.026, p = 0.002) and to the number of previous live births (0.291, p = 0.016). In multivariate analysis, both serum P (- 0.1; p = 0.015) and P per oocyte (- 1.347, p = 0.002) maintained the significant inverse association with birthweight z-score after adjusting for height and parity.

CONCLUSIONS

Serum progesterone level on the day of ovulation trigger inversely correlates with normalized birthweight of neonates in segmented GnRH antagonist ART cycles.

Effect of serum progesterone on human chorionic gonadotropin trigger day / metaphase II oocyte ratio on pregnancy and neonatal outcomes in women undergoing ICSI cycle

BACKGROUND

The serum progesterone on human chorionic gonadotropin trigger day / metaphase II oocyte (P/MII) ratio might be a more predictable indicator of pregnancy and neonatal outcomes as compare to P/estradiol (E2) or P alone. Hence, we conducted a larger population study to compare the pregnancy and neonatal outcomes in the low and high P/MII ratio.

METHODS

A retrospective, single-center, larger population cohort study between January 2015 and August 2021. Calculate the threshold effect of P/MII ratio on clinical pregnancy rate according to the construct smooth curve fitting. Divide data into two groups by threshold for comparison.

RESULTS

3566 fresh ICSI-ET cycles were included, in which 929 singleton delivery and 676 twin deliveries. Compare to P/MII ≤ 0.367 group, it indicated that the P/MII > 0.367 group had a lower clinical pregnancy rate and live birth rate, furthermore, a significantly higher rate of LBW and SGA were observed in the singleton and twin deliveries. No deleterious impact of high P/MII ratio on embryo quality and undesirable pregnancy outcomes was shown.

CONCLUSIONS

When P/MII is higher than 0.367, may have adverse impacts on pregnancy and neonatal outcomes for ICSI cycle.

Effect of Frozen-Thawed Embryo Transfer on the Metabolism of Children in Early Childhood

Background: As a routine procedure in assisted reproductive technology (ART), it is crucial to assess the safety of frozen and thawed embryo transfer (FET). We aimed to investigate the metabolic profile of children conceived through FET in their early childhood. Method: A total of 147 children between the age of 1.5 and 4 years old, conceived through FET or naturally conceived (NC), were recruited. A total of 89 children, 65 in the FET group and 24 in the NC group (matched with the FET group based on children’s BMI) were included in the final statistical analysis of biochemical markers and metabolomics. Results: Children conceived through FET had a lower level of fasting insulin level and HORM-IR and a higher level of fasting glucose and APOE as compared to children naturally conceived. Metabolomics showed that there were 16 small differential metabolites, mainly including amino acids, carnitines, organic acids, butyric, and secondary bile acid between two groups, which enriched in Nitrogen metabolism, Butanoate metabolism, Phenylalanine metabolism, and D-Arginine and D-ornithine metabolism pathways. Conclusion: Although the FET group had a significantly higher level of APOE and fasting glucose, it cannot yet be considered that children in the FET group had an obvious disorder of glucose and lipid metabolism. However, the potentially more active intestinal flora and lower carnitine levels of children in the FET group suggested by metabolomics are worth further exploration.

Risk factors associated with preterm birth in singletons born after IVF: a national cohort study

RESEARCH QUESTION

What are the risk factors for prematurity other than intrauterine growth restriction in singletons after IVF?

DESIGN

Data were collected from a national registry, based on an observational prospective cohort of 30,737 live births after assisted reproductive technology (fresh embryo transfers: n = 20,932 and frozen embryo transfer [FET] n = 9805) between 2014 and 2015. A population of not-small for gestational age singletons conceived after fresh embryo transfers and FET, and their parents, was selected. Data on a number of variables were collected, including type of infertility, number of oocytes retrieved and vanishing twins.

RESULTS

Preterm birth occurred in 7.7% (n = 1607) of fresh embryo transfers and 6.2% (n = 611) of frozen-thawed embryo transfers (P < 0.0001; adjusted odds ratio [aOR] = 1.34 [1.21-1.49]). Endometriosis and vanishing twin increased the risk of preterm birth after fresh embryo transfer (P < 0.001; aOR 1.32 and 1.78, respectively). Polycystic ovaries or more than 20 oocytes retrieved also increased preterm birth risk (aOR 1.31 and 1.30; P = 0.003 and P = 0.02, respectively); large oocyte cohort (>20) was no longer associated with the risk of prematurity in FET.

CONCLUSION

Endometriosis remains a risk for prematurity even in the absence of intrauterine growth retardation, which suggests a dysimmune effect. Large oocyte cohorts obtained by stimulation, without clinical polycystic ovary syndrome diagnosed before attempts, do not affect FET outcomes, reinforcing the idea of a phenotypic difference in the clinical presentation of polycystic ovary syndrome.

Impact of cell loss after warming of human vitrified day 3 embryos on obstetric outcome in single frozen embryo transfers

PURPOSE

Does cell loss (CL) after vitrification and warming (V/W) of day 3 embryos have an impact on live birth rate (LBR) and neonatal outcomes?

METHOD

This retrospective analysis includes cleavage stage day 3 embryos vitrified/warmed between 2011 and 2018. Only single vitrified/warmed embryo transfers were included. Pre-implantation genetic screening, oocyte donation, and age banking were excluded from the analysis. The sample was divided into two groups: group A (intact embryo after warming) and group B (≤ 50% blastomere loss after warming).

RESULTS

On the total embryos (n = 2327), 1953 were fully intact (83.9%, group A) and 374 presented cell damage (16.1%, group B). In group B, 62% (232/374) of the embryos had lost only one cell. Age at cryopreservation, cause of infertility, insemination procedure, and semen origin were comparable between the two groups. The positive hCG rate (30% and 24.3%, respectively, for intact vs CL group, p = 0.028) and LBR (13.7% and 9.4%, respectively, for intact vs CL group, p = 0.023) per warming cycle were significantly higher for intact embryos. However, LBR per positive hCG was equivalent between intact and damaged embryos (45.6% vs 38.5%, respectively, p = 0.2). Newborn measurements (length, weight, and head circumference at birth) were comparable between the two groups. Multivariate logistic regression showed that the presence of CL is not predictive for LB when adjusting for patients' age.

CONCLUSIONS

LBR is significantly higher after transfer of an intact embryo compared to an embryo with CL after warming; however, neonatal outcomes are comparable between the two groups.

Comparison of Perinatal Outcomes of Letrozole-Induced Ovulation and Hormone Replacement Therapy Protocols in Patients With Abnormal Ovulation Undergoing Frozen-Thawed Embryo Transfer: A Propensity Score Matching Analysis

BACKGROUND

With the increasing use of frozen embryo transfer (FET), the best endometrial preparation protocol is continuously being discussed. The hormone replacement therapy (HRT) cycle and letrozole-induced ovulation (L-OI) cycle are available protocols for patients with abnormal ovulation. Previous comparisons of the two protocols have focused on pregnancy outcomes, with less attention to perinatal outcomes, and population heterogeneity was large; thus, convincing conclusions about which protocol is more appropriate could not be drawn.

METHODS

We performed a retrospective cohort study using propensity score matching (PSM) analysis for a population of patients undergoing FET cycles in the reproductive center of the Third Affiliated Hospital of Zhengzhou University from January 2016 to September 2020. The main outcome measures were clinical pregnancy rate, live birth rate, very preterm delivery (VPTD), preterm delivery (PTD), low birth weight (LBW), macrosomia, small for gestational age (SGA), large for gestational age (LGA), hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus (GDM), premature rupture of membranes (PROM), placenta previa, and congenital abnormality.

RESULTS

A total of 8010 women were enrolled. Due to the large heterogeneity among the patients, we conducted 1:1 PSM, and 1461 women matched in each group. Compared with the HRT group, the L-OI group had a smaller proportion of thin endometrium (27.38% vs. 41.07%) and thicker endometrium on the day of embryo transfer (9.63 ± 1.82 vs. 8.91 ± 1.38). There were no significant differences in clinical pregnancy rate, early abortion rate or live birth rate between the groups. There was no significant difference in perinatal outcomes of singleton live birth, including VPTD, PTD, postterm delivery, LBW, macrosomia, SGA, LGA, GDM, HDP, placenta previa, and congenital malformation.

CONCLUSION

For women with abnormal ovulation, the pregnancy and perinatal outcomes of HRT and L-OI protocols are reassuring. It seems that both protocols are safe and effective for endometrial preparation in frozen-thawed embryo transfer in the clinic.

Impact of the type of endometrial oestrogen preparation for frozen-thawed embryo (vaginal or transdermal) on perinatal outcomes in an artificial cycle

INTRODUCTION

Serum oestradiol concentration at the time of frozen embryo transfer (FET) in artificial cycle are lower when using transdermal administration of oestrogen for endometrial preparation compared to the vaginal route. This difference could have consequences for placentation and establishment of maternal-foetal circulation. The aim of our study was to compare the birth weight of newborns and the perinatal issues after FET in an artificial cycle with regard to the route of administration of oestrogens.

METHODS

Retrospective monocentric cohort study in the medically assisted reproduction department of the University Hospital of Angers, France, between January 2017 and October 2020. Inclusion criteria were age >18 years old and one live birth after FET in an artificial cycle. The main outcome was the birth weight of the newborns. The choice of oestrogens administration (transdermal or vaginal) was left to the patient.

RESULTS

804 FET in artificial cycle were included in our study. Oestrogens were administrated in 356/804(36.6%) patients using transdermal route and in 448/804(45.9%) patients using vaginal route. There were 68/345 (19.1%) live births in the transdermal group and 85/448 (19%) in the vaginal group. There was no difference in the birth weight of the newborns (3320[2100-4165] grams in the transdermal group vs 3327.5[915-4650] grams in the vaginal group, p=0.72). All the other perinatal issues were comparable between the two groups.

CONCLUSION

Birth weights and perinatal issues were comparable with regard to the route of administration of oestrogens (vaginal or transdermal) in the context of endometrial preparation before FET in an artificial cycle.

The incidence of small for gestational age neonates in singleton IVF pregnancies

INTRODUCTION

Various factors related to an "in vitro" fertilization (IVF) procedure may influence the rate of small for gestational age (SGA) newborns in such pregnancies.

AIM

The aim of the study was to determine neonatal SGA incidence in singleton IVF pregnancies compared to spontaneous ones.

MATERIALS AND METHODS

We conducted both a prospective and a retrospective study within the period of January 2013-December 2017, which included 336 patients with a singleton IVF pregnancy at the time of delivery - the study group (SG), and 493 women with a spontaneous conception - the control group (CG).

RESULTS

Neonatal SGA rate was significantly higher in the SG as compared to the CG, p < .05, as well as in case of multiple embryotransfer (ET), vanishing twin syndrome (VTS), fresh ET against frozen embryotransfer (FET), female infertility factor.

CONCLUSION

Singleton pregnancies after an IVF technique show a higher neonatal SGA rate compared to spontaneous ones.

A systematic review and meta-analysis on the association between ICSI and chromosome abnormalities

BACKGROUND

In the decade following the introduction of ICSI, a higher prevalence of de novo chromosome abnormalities, in particular sex chromosome and autosomal structural abnormalities, as well as inherited abnormalities was described in children conceived by ICSI compared to both naturally conceived (NC) children and children conceived by standard IVF. The explanation for the observed increase in prevalence is not clear and has been suggested to reflect parental factors (e.g. age or sperm quality) or to be a result of the ICSI procedure itself. Over the years, the procedure, as well as the patient group, and indications for ICSI treatment have changed.

OBJECTIVE AND RATIONALE

The objective of this systematic review and meta-analysis was to assess the prevalence of chromosome abnormalities in ICSI pregnancies and children and to examine any potentially increased risk compared to standard IVF and NC.

SEARCH METHODS

Pubmed, Embase, Cochrane Libraries and Web of Science up to October 2020 were searched. Primary outcome measures were overall chromosome abnormalities and de novo abnormalities (including sex chromosome abnormalities and autosomal abnormalities). The secondary outcome was inherited abnormalities. We followed the PRISMA guidelines and relevant meta-analyses were performed.

OUTCOMES

The search included 4648 articles, out of which 27 met the inclusion criteria, and 19 were included in quantitative synthesis (meta-analyses). The prevalence of chromosome abnormalities varied considerably between studies, possibly explained by large differences in sample size and patient demographics. Only five studies were eligible for pooled analyses on adjusted data. All studies had a critical risk of bias. Results from pooled adjusted data showed no evidence of an increased risk of overall chromosome abnormalities when comparing ICSI to either standard IVF (aOR 0.75 (95% CI 0.41-1.38)) or NC (aOR 1.29 (95% CI 0.69-2.43)). In contrast, meta-analyses on unadjusted data showed an increased risk of overall chromosome abnormalities in ICSI compared to both standard IVF (OR 1.42 (95% CI 1.09-1.85)) and NC (OR 2.46 (95% CI 1.52-3.99)) and an increased risk of de novo abnormalities in ICSI compared to NC (OR 2.62 (95% CI 2.07-3.31)). Yet, based on a very low certainty of evidence, the conclusion remains, that no indication of an increased risk of chromosome abnormalities in ICSI offspring could be found. If an increased risk of chromosome abnormalities in selected ICSI offspring should exist, the absolute risk continues to be small.

WIDER IMPLICATIONS

This review provides an extensive overview of the existing evidence on the relationship between ICSI and chromosome abnormalities in the offspring. We highlight the need for well-designed large, prospective, controlled studies with systematic cytogenetic testing. Existing data are limited and, in many cases, marred by critical levels of bias.

The effect of repeated cryopreservation and thawing using cryotip on the clinical outcomes of embryos

PURPOSE

To compare the clinical outcomes of embryo transfers that were cryopreserved and thawed two or three times with those cryopreserved and thawed once by CryoTip.

METHODS

Data for 388 single cryopreserved-thawed blastocyst transfer cycles, performed from April 2012 to March 2014, were assessed. The blastocysts were classified into three groups: blastocysts (A) cryopreserved once, (B) cryopreserved twice, and (C) cryopreserved three times.

RESULTS

The pregnancy rate was 43.8% (134/306) in group A and 46.3% (38/82) in group B, while the miscarriage rate was 29.1% (39/134) in group A and 23.7% (9/38) in group B. The rate of improvement/maintenance of blastocyst grade was 84.0% (257/306) in group A and 80.5% (66/82) in group B. The pregnancy and miscarriage rates of the blastocysts that showed improvement/maintenance in the grade were 45.9% (118/257) and 29.7% (35/118) in group A and 48.5% (32/66) and 21.9% (7/32) in group B, respectively. The pregnancy rate was 33.3% (2/6), while the miscarriage rate was 0.0% (0/2) in group C.

CONCLUSIONS

Pregnancy rates achieved with re-cryopreserved and rethawed blastocyst transfer were comparable to those achieved with single cryopreserved-thawed blastocyst transfer.

Ovulatory-Based FET Cycles May Achieve Higher Pregnancy Rates in the General Population and among Anovulatory Women

This study evaluated which endometrial preparation protocol in frozen embryo transfer (FET) cycles provides the best results for polycystic ovarian syndrome (PCOS) patients and the general population. This retrospective study of 634 FET cycles was conducted 2016-2018. Cycles were divided into Group A: Artificial endometrial preparations for FET (aFET; n = 348), Group B: Ovulatory cycle (n = 286) to compare two methods of endometrial preparation for FET. Artificial endometrial preparation with exogenous estrogen and progesterone versus natural ovulation cycles, modified natural cycles using hCG for the final triggering and letrozole-induced ovulation with hCG. Anovulatory patients were analyzed separately. Anovulatory PCOS patients had significantly higher pregnancy rates with letrozole treatment compared with aFET cycles (44% vs. 22.5%; p = 0.044). For the entire cohort, ovulatory cycles and aFET were similar in terms of patient characteristics, demographics, infertility causes, treatment protocols and number of embryos transferred. Although the mean ESHRE score of the transferred embryos was higher in the aFET group, we found higher clinical pregnancy rate in the ovulatory cycle FET (41.3% vs. 27.3%, p < 0.0001). A better pregnancy rate was found after ovulatory cycle FET. In the ovulatory cycles, the outcome of letrozole-induced and non-induced cycles were comparable. PCOS patients, as well as the general population, may benefit from ovulation induced FET cycles, with significantly better outcomes in FET in ovulatory cycles.

Developmental outcomes in children from cryopreserved embryos compared to their siblings from fresh embryo transfers: a case series

OBJECTIVE

This study aimed to evaluate the developmental outcomes in children from cryopreserved embryos, with minimum influences of interparental variation that would cause potential bias. Hence we examined siblings, in which the older sibs were from fresh embryo transfers, while the younger sibs were from cryopreserved embryos.

METHODS

Three pairs of siblings were evaluated. All routine prenatal and neonatal evaluation were performed, while personal-social, language, fine and gross motor evaluation were all evaluated by the Denver Developmental Screening Test (DDST)-II. Wechsler Preschool and Primary Scale of Intelligence (WPPSI) test was used to measure the Intelligent Quotient (IQ) in 5 of 6 children.

RESULTS

Standard prenatal measurements of all children suggested uneventful pregnancies, followed by uneventful deliveries. DDST-II results showed that the aspects of personal-social, language, fine and gross motor in every child are as expected according to their ages. Results from WPPSI tests suggest that 5 of 6 evaluated children acquired average to high-average intelligences.

CONCLUSIONS

The results suggest that the developmental outcomes in children from cryopreserved embryos have no significant differences with the outcomes in children from fresh embryo transfers.

The risk of birth defects with conception by ART

STUDY QUESTION

What is the association between ART conception and treatment parameters and the risk of birth defects?

SUMMARY ANSWER

Compared to naturally conceived singleton infants, the risk of a major nonchromosomal defect among ART singletons conceived with autologous oocytes and fresh embryos without use of ICSI was increased by 18%, with increases of 42% and 30% for use of ICSI with and without male factor diagnosis, respectively.

WHAT IS KNOWN ALREADY

Prior studies have indicated that infertility and ART are associated with an increased risk of birth defects but have been limited by small sample size and inadequate statistical power, failure to differentiate results by plurality, differences in birth defect definitions and methods of ascertainment, lack of information on ART treatment parameters or study periods spanning decades resulting in a substantial historical bias as ART techniques have improved.

STUDY DESIGN, SIZE, DURATION

This was a population-based cohort study linking ART cycles reported to the Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) from 1 January 2004 to 31 December 2015 that resulted in live births from 1 September 2004 to 31 December 2016 in Massachusetts and North Carolina and from 1 September 2004 to 31 December 2015 for Texas and New York: these were large and ethnically diverse States, with birth defect registries utilizing the same case definitions and data collected, and with high numbers of ART births annually. A 10:1 sample of non-ART births were chosen within the same time period as the ART birth. Naturally conceived ART siblings were identified through the mother's information. Non-ART children were classified as being born to women who conceived with ovulation induction (OI)/IUI when there was an indication of infertility treatment on the birth certificate, but the woman did not link to the SART CORS; all others were classified as being naturally conceived.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study population included 135 051 ART children (78 362 singletons and 56 689 twins), 23 647 naturally conceived ART siblings (22 301 singletons and 1346 twins) and 9396 children born to women treated with OI/IUI (6597 singletons and 2799 twins) and 1 067 922 naturally conceived children (1 037 757 singletons and 30 165 twins). All study children were linked to their respective State birth defect registries to identify major defects diagnosed within the first year of life. We classified children with major defects as either chromosomal (i.e. presence of a chromosomal defect with or without any other major defect) or nonchromosomal (i.e. presence of a major defect but having no chromosomal defect), or all major defects (chromosomal and nonchromosomal). Logistic regression models were used to generate adjusted odds ratios (AORs) and 95% CI to evaluate the risk of birth defects due to conception with ART (using autologous oocytes and fresh embryos), and with and without the use of ICSI in the absence or presence of male factor infertility, with naturally conceived children as the reference. Analyses within the ART group were stratified by combinations of oocyte source (autologous, donor) and embryo state (fresh, thawed), with births from autologous oocytes and fresh embryos as the reference. Analyses limited to fresh embryos were stratified by oocyte source (autologous, donor) and the use of ICSI. Triplets and higher-order multiples were excluded.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 21 998 singleton children (1.9%) and 3037 twin children (3.3%) had a major birth defect. Compared to naturally conceived children, ART singletons (conceived from autologous oocytes, fresh embryos without the use of ICSI) had increased risks of a major nonchromosomal birth defect (AOR 1.18, 95% 1.05, 1.32), cardiovascular defects (AOR 1.20, 95% CI 1.03, 1.40), and any birth defect (AOR 1.18, 95% CI 1.09, 1.27). Compared to naturally conceived children, ART singletons conceived (from autologous oocytes, fresh embryos) with the use of ICSI, the risks were increased for a major nonchromosomal birth defect (AOR 1.30, 95% CI 1.16, 1.45 without male factor diagnosis; AOR 1.42, 95% CI 1.28, 1.57 with male factor diagnosis); blastogenesis defects (AOR 1.49, 95% CI 1.08, 2.05 without male factor; AOR 1.56, 95% CI 1.17, 2.08 with male factor); cardiovascular defects (AOR 1.28, 95% CI 1.10,1.48 without male factor; AOR 1.45, 95% CI 1.27, 1.66 with male factor); in addition, the risk for musculoskeletal defects was increased (AOR 1.34, 95% CI 1.01, 1.78 without male factor) and the risk for genitourinary defects in male infants was increased (AOR 1.33, 95% CI 1.08, 1.65 with male factor). Comparisons within ART singleton births conceived from autologous oocytes and fresh embryos indicated that the use of ICSI was associated with increased risks of a major nonchromosomal birth defect (AOR 1.18, 95% CI 1.03, 1.35), blastogenesis defects (AOR 1.65, 95% CI 1.08, 2.51), gastrointestinal defects (AOR 2.21, 95% CI 1.28, 3.82) and any defect (AOR 1.11, 95% CI 1.01, 1.22). Compared to naturally conceived children, ART singleton siblings had increased risks of musculoskeletal defects (AOR 1.32, 95% CI 1.04, 1.67) and any defect (AOR 1.15, 95% CI 1.08, 1.23). ART twins (conceived with autologous oocytes, fresh embryos, without ICSI) were at increased risk of chromosomal defects (AOR 1.89, 95% CI 1.10, 3.24) and ART twin siblings were at increased risk of any defect (AOR 1.26, 95% CI 1.01, 1.57). The 18% increased risk of a major nonchromosomal birth defect in singleton infants conceived with ART without ICSI (∼36% of ART births), the 30% increased risk with ICSI without male factor (∼33% of ART births), and the 42% increased risk with ICSI and male factor (∼31% of ART births) translates into an estimated excess of 386 major birth defects among the 68 908 singleton children born by ART in 2017.

LIMITATIONS, REASONS FOR CAUTION

In the SART CORS database, it was not possible to differentiate method of embryo freezing (slow freezing vs vitrification), and data on ICSI was only available in the fresh embryo ART group. In the OI/IUI group, it was not possible to differentiate type of non-ART treatment utilized, and in both the ART and OI/IUI groups, data were unavailable on duration of infertility.

WIDER IMPLICATIONS OF THE FINDINGS

The use of ART is associated with increased risks of a major nonchromosomal birth defect, cardiovascular defect and any defect in singleton children, and chromosomal defects in twins; the use of ICSI further increases this risk, the most with male factor infertility. These findings support the judicious use of ICSI only when medically indicated. The relative contribution of ART treatment parameters versus the biology of the subfertile couple to this increased risk remains unclear and warrants further study.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by grant R01 HD084377 from the National Institute of Child Health and Human Development. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Child Health and Human Development, or the National Institutes of Health, nor any of the State Departments of Health which contributed data. E.W. is a contract vendor for SART; all other authors report no conflicts.

TRIAL REGISTRATION NUMBER

N/A.

Perinatal and obstetric outcomes in singleton pregnancies following fresh versus cryopreserved blastocyst transfer: a meta-analysis

The transfer of cryopreserved blastocysts is increasing in IVF centres. However, little is known about the perinatal and obstetric outcomes of this procedure. In an attempt to further elucidate these issues, a systematic review and meta-analysis was conducted to compare cryopreserved transfer with fresh blastocyst embryo transfer. The results show that the risk of both preterm (odds ratio [OR] 0.89, 95% confidence interval [CI] 0.80-0.99, P = 0.04) and low birthweight births (OR 0.82, 95% CI 0.68-0.99, P = 0.04) was significantly lower after cryopreserved blastocyst transfer than after fresh blastocyst transfer. The rate of large for gestational age births was significantly higher (OR 1.68, 95% CI 1.55-1.82, P < 0.00001) and the rate of small for gestational age births significantly lower (OR 0.59, 95% CI 0.54-0.65, P < 0.00001) after cryopreserved blastocyst transfer. The transfer of cryopreserved blastocysts was associated with a significantly lower risk of placental abruption (OR 0.58, 95% CI 0.40-0.83, P = 0.003) but a significantly higher risk of Caesarean section (OR 1.21, 95% CI 1.01-1.43, P = 0.03). In conclusion, the perinatal and obstetric outcomes associated with the transfer of cryopreserved blastocysts differ from those associated with fresh blastocyst transfer.

Current evidence supporting a goal of singletons: a review of maternal and perinatal outcomes associated with twin versus singleton pregnancies after in vitro fertilization and intracytoplasmic sperm injection

With increasing use of in vitro fertilization and intracytoplasmic sperm injection (IVF-ICSI) almost 2% of all babies born in the United States each year are now conceived with these technologies, making outcomes of IVF-ICSI extremely important not only to patients and families but to public health. Twin pregnancy rates after IVF-ICSI in the United States have declined since their peak in 2013 but remain at approximately 1 in 10 to 1 in 20 pregnancies. A review of the current international literature on twin versus singleton pregnancy outcomes after IVF-ICSI treatment confirms statistically significantly higher risks to maternal and perinatal health and statistically significantly higher health care costs. The field of infertility care should continue to work to develop practices that lower twin pregnancy rates to an absolute minimum to maximize the safety of these medical treatments.

Which is better for mothers and babies: fresh or frozen-thawed blastocyst transfer?

BACKGROUND

In recent years, there have been many reports on the pregnancy outcomes of fresh blastocyst transfer (BT) and frozen-thawed BT, but the conclusions are controversial and incomplete. To compare the pregnancy outcomes, maternal complications and neonatal outcomes of fresh and frozen-thawed BT in the context of in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) cycles, we conducted a meta-analysis.

METHODS

A meta-analysis was conducted by searching the PubMed, Embase, and Cochrane Library databases through May 2020. Data were extracted independently by two authors.

RESULTS

Fifty-four studies, including 12 randomized controlled trials (RCTs), met the inclusion criteria. Fresh BT was associated with a lower implantation rate, pregnancy rate, ongoing pregnancy rate, and clinical pregnancy rate and higher ectopic pregnancy rate than frozen-thawed BT according to the results of the RCTs. The risks of moderate or severe ovarian hyperstimulation syndrome, placental abruption, placenta previa and preterm delivery were higher for fresh BT than for frozen-thawed BT. The risk of pregnancy-induced hypertension and pre-eclampsia was lower for fresh BT; however, no significant differences in risks for gestational diabetes mellitus and preterm rupture of membrane were found between the two groups. Compared with frozen-thawed BT, fresh BT appears to be associated with small for gestational age and low birth weight. No differences in the incidences of neonatal mortality or neonatal malformation were observed between fresh and frozen-thawed BT.

CONCLUSIONS

At present there is an overall slight preponderance of risks in fresh cycles against frozen, however individualization is required and current knowledge does not permit to address a defintive response.

Effects of oocyte vitrification on the behaviors and physiological indexes of aged first filial generation mice

To evaluate the long-term effects of oocyte cryopreservation on the health of the first filial generation (F1), we used B6D2F1 mice for oocyte collection, in vitro fertilization, and breeding. The female F1 mice born from the offspring of fresh mature oocytes (control group) and from the offspring of vitrified oocytes with traditional vitrification medium (VM group) and new improved vitrification medium (2P10E7D group) were maintained until 14-15 months of age for behavioral tests and 16-17 months of age for physiological analyses. Behavioral indexes, including anxiety-like status, discrimination ability, learning and memory ability, were investigated. Physiological indexes including body weight, body fat, heart rate, blood pressure, and blood lipids were also analyzed. In our results, the behavioral indexes, body weight, body fat, heart rate, blood pressure, total cholesterol (TC), high-density lipoprotein cholesterol (HDL), and low-density lipoprotein cholesterol (LDL) did not show significant differences among the three groups. However, the triglyceride (TG) level of the VM group was higher than that of the 2P10E7D group. Moreover, compared with the control group, both the VM group and the 2P10E7D group showed greatly increased diastolic blood pressure. This study is the first to report that oocyte vitrification might affect metabolic physiological indexes via transgenerational inheritance rather than behaviors related to anxiety-like status and cognitive ability. Furthermore, different vitrification media might have differential transgenerational effects.

Increased risk of maternal and neonatal complications in hormone replacement therapy cycles in frozen embryo transfer

BACKGROUND

The endometrial preparation during frozen embryo transfer (FET) can be performed by natural cycle (NC), hormone replacement therapy (HRT) cycle and cycle with ovulation induction (OI). Whether different FET preparation protocols can affect maternal and neonatal outcomes is still inconclusive.

METHODS

This was a retrospective cohort study that included 6886 women who delivered singleton live birth babies after 28 weeks of pregnancy underwent FET from January, 2015 to July, 2018. Women were divided into three groups according to the protocols used for endometrial preparation during FET: NC group (N = 4727), HRT group (N = 1642) and OI group (N = 517).

RESULTS

After adjusting for the effect of age, body mass index (BMI), irregular menstruation, antral follicle count (AFC), endometrial thickness, the levels of testosterone, anti-Müllerian hormone (AMH), preconceptional fasting glucose (PFG), systolic and diastolic pressure et al., the HRT group had higher risk of hypertensive disorders of pregnancy (HDP) compared with the NC group (adjusted odds ratio (aOR) 2.00, 95% confidence interval (CI) 1.54-2.60). Singletons born after HRT FET were at increased risk of low birth weight (LBW) compared to NC group (aOR 1.49, 95%CI 1.09-2.06). The risks of preterm birth (PTB) in the HRT and OI group were elevated compared with the NC group (aOR 1.78, 95%CI 1.39-2.28 and aOR 1.51, 95%CI 1.02-2.23, respectively).

CONCLUSIONS

The HRT protocol for endometrial preparation during frozen embryo transfer of blastocysts was associated with increased risk of maternal and neonatal complications, compared to the NC and OI protocol.

Metabolic profile of in vitro derived human embryos is not affected by the mode of fertilization

The pattern of metabolism by early embryos in vitro has been linked to a range of phenotypes, including viability. However, the extent to which metabolic function of embryos is modified by specific methods used during ART has yet to be fully described. This study has sought to determine if the mode of fertilization used to create embryos affects subsequent embryo metabolism of substrates. A metabolic profile, including consumption of key substrates and the endogenous triglyceride content of individual IVF and ICSI supernumerary embryos, was assessed and compared. Embryo development and quality was also recorded. All embryos were donated at a single clinical IVF center, on Day 5, from 36 patients aged 18-38 years, The data revealed that consumption of glucose and pyruvate, and production of lactate, did not differ between embryos created by IVF or ICSI. Similarly, the mode of insemination did not impact on the triglyceride content of embryos. However, ICSI-derived embryos displayed a more active turnover of amino acids (P = 0.023), compared to IVF embryos. The specific amino acids produced in higher quantities from ICSI compared to IVF embryos were aspartate (P = 0.016), asparagine (P = 0.04), histidine (P = 0.021) and threonine (P = 0.009) while leucine consumption was significantly lower (P = 0.04). However, importantly neither individual nor collective differences in amino acid metabolism were apparent for sibling oocytes subjected to either mode of fertilization. Embryo morphology (the number of top grade embryos) and development (proportion reaching the blastocyst stage) were comparable in patients undergoing IVF and ICSI. In conclusion, the microinjection of spermatozoa into oocytes does not appear to have an impact on subsequent metabolism and viability. Observed differences in amino acid metabolism may be attributed to male factor infertility of the patients rather than the ICSI procedure per se.

The impact of chorionicity and assisted reproductive therapies in obstetric and neonatal outcomes

Objective: Multiple gestations' incidence have raised worldwide in the last years, much due to assisted reproductive therapies (ART). The goal of this study was to analyze obstetric and neonatal outcomes of twin pregnancies in a level 3 maternity.Methods: A retrospective study including all twins born in a period of 12 years in a level 3 maternity was conducted. Analysis comparing spontaneous monochorionic and dichorionic twins and spontaneous and ART dichorionic twins were performed. A p value < .05 was considered statistically significant.Results: The sample included 1783 newborns from 875 mothers. Mean maternal age was 31 years, with 616 spontaneous pregnancies and 259 through ART. Prematurity occurred in 77%. Congenital malformations were found in 6%, and the mortality rate was 3%. Monochorionic twins had higher prematurity (79% vs 72%) and very low birthweight (VLBW) rate (19% vs 14%). Congenital anomalies (9% vs 6%), Respiratory Distress Syndrome (23% vs 18%), patent ductus arteriosus (7% vs 4%), anemia (11% vs 5%), periventricular hemorrhage (5% vs 3%), mechanical ventilation (16% vs 10%) and mortality (4% vs 2%) were higher in monochorionic twins. Although congenital malformations were more frequent in the ART group, the difference was not statistically significant. The effect of ART in neonatal and obstetric outcomes was related to maternal age.Conclusion: Monochorionic pregnancies were associated with worst obstetric and neonatal outcomes. Although congenital malformations were more frequent in the ART group, the difference was not statistically significant. Most obstetric and neonatal complications were related to advanced maternal age.

Live birth rates with a freeze-only strategy versus fresh embryo transfer: secondary analysis of a randomized clinical trial

RESEARCH QUESTION

What are the roles of serum progesterone and endometrial thickness as biomarkers in the decision between a freeze-only and fresh embryo transfer in IVF for women without polycystic ovary syndrome (PCOS)?

DESIGN

This was a secondary analysis of a randomized controlled trial including 782 couples who were followed up until the end of the first completed cycle. Couples scheduled for their first or second IVF cycle with a FSH/gonadotrophin-releasing hormone antagonist protocol were randomized to a freeze-only (n = 391) or fresh embryo transfer (n = 391) strategy. The endpoint for this analysis was live birth rate (LBR) after the first embryo transfer.

RESULTS

There was no significant difference in LBR after the first cycle between a freeze-only and fresh transfer strategy. When serum progesterone levels at trigger were in the third quartile (Q3, 1.14-1.53 ng/ml), LBR was significantly higher in the freeze-only versus fresh transfer group (P = 0.01); when serum progesterone was ≥1.14 ng/ml, LBR was significantly better in the freeze-only group (37.4% versus 23.8% in the fresh transfer group; P = 0.004). LBRs in the freeze-only and fresh embryo transfer groups were similar across all quartiles of endometrial thickness, although a small advantage for freeze-only in women with a very thin endometrium could not be excluded.

CONCLUSIONS

Serum progesterone level on the day of trigger may have potential as a biomarker on which to base a prospective decision about whether to use a freeze-only or fresh embryo transfer strategy in women undergoing IVF.

The growth of assisted reproductive treatment-conceived children from birth to 5 years: a national cohort study

BACKGROUND

Birth weight and early child growth are important predictors of long-term cardiometabolic disease risk, in line with the Developmental Origins of Health and Disease hypothesis. As human assisted reproductive technologies (ARTs) occur during the sensitive periconceptional window of development, it has recently become a matter of urgency to investigate risk in ART-conceived children.

METHODS

We have conducted the first large-scale, national cohort study of early growth in ART children from birth to school age, linking the register of ART, held by the UK's Human Fertilisation and Embryology Authority, to Scottish maternity and child health databases.

RESULTS

In this study of 5200 ART and 20,800 naturally conceived (NC) control children, linear regression analysis revealed the birthweight of babies born from fresh embryo transfer cycles is 93.7 g [95% CI (76.6, 110.6)g] less than NC controls, whereas babies born from frozen embryo transfer (FET) cycles are 57.5 g [95% CI (30.7, 86.5)g] heavier. Fresh ART babies grew faster from birth (by 7.2 g/week) but remained lighter (by 171 g), at 6-8 weeks, than NC babies and 133 g smaller than FET babies; FET and NC babies were similar. Length and occipital-frontal circumference followed the same pattern. By school entry (4-7 years), weight, length and BMI in boys and girls conceived by fresh ART and FET were similar to those in NC children.

CONCLUSIONS

ART babies born from fresh embryo transfer grow more slowly in utero and in the first few weeks of life, but then show postnatal catch up growth by school age, compared to NC and FET babies. As low birth weight and postnatal catch-up are independent risk factors for cardiometabolic disease over the life-course, we suggest that further studies in this area are now warranted.

Risk of prematurity and infant morbidity and mortality by maternal fertility status and plurality

PURPOSE

To evaluate the risk of prematurity and infant mortality by maternal fertility status, and for in vitro fertilization (IVF) pregnancies, by oocyte source and embryo state combinations.

METHODS

Women in 14 States who had IVF-conceived live births during 2004-13 were linked to their infant's birth and death certificates; a 10:1 sample of non-IVF births was selected for comparison; those with an indication of infertility treatment on the birth certificate were categorized as subfertile, all others were categorized as fertile. Risks were modeled separately for the fertile/subfertile/IVF (autologous-fresh only) group and for the IVF group by oocyte source-embryo state combinations, using logistic regression, and reported as adjusted odds ratios (AORs) and 95% confidence intervals (CI).

RESULTS

The study population included 2,474,195 pregnancies. Placental complications (placenta previa, abruptio placenta, and other excessive bleeding) and prematurity were both increased with pregestational and gestational diabetes and hypertension, among subfertile and IVF groups, and in IVF pregnancies using donor oocytes. Both subfertile and IVF pregnancies were at risk for prematurity and NICU admission; IVF infants were also at risk for small-for-gestation birthweight, and subfertile infants had greater risks for neonatal and infant death. Within the IVF group, pregnancies with donor oocytes and/or thawed embryos were at greater risk of large-for-gestation birthweight, and pregnancies with thawed embryos were at greater risk of neonatal and infant death.

CONCLUSIONS

Prematurity was associated with placental complications, diabetes and hypertension, subfertility and IVF groups, and in IVF pregnancies, donor oocytes and/or thawed embryos.

Obstetric outcomes after fresh versus frozen-thawed embryo transfers: A systematic review and meta-analysis

Objective

To evaluate if there are differences in the risks of obstetric outcomes in IVF/ICSI singleton pregnancies when compared fresh to frozen-thawed embryo transfers (FET).

Methods

This was a systematic review and meta-analysis evaluating the obstetric outcomes in singleton pregnancies after FET and fresh embryo transfer. The outcomes included in this study were pregnancy-induced hypertension (PIH), pre-eclampsia, placenta previa, and placenta accreta.

Results

The search yielded 654 papers, 6 of which met the inclusion criteria and reported on obstetric outcomes. When comparing pregnancies that arose from FET or fresh embryo transfer, there was an increase in the risk of obstetric complications in pregnancies resulting from FET when compared to those emerging from fresh embryo transfers in PIH (aOR 1.82; 95% CI 1.24-2.68), pre-eclampsia (aOR 1.32, 95% CI 1.07, 1.63), and placenta accreta (aOR 3.51, 95% CI 2.04-6.05). There were no significant differences in the risk between the FET and fresh embryo transfer groups when evaluating placenta previa (aOR 0.70; 95% CI 0.46-1.08).

Conclusion

The obstetric outcomes observed in pregnancies arising from ART may differ among fresh and FET cycles. Thus, when evaluating to perform a fresh embryo transfer or a freeze-all cycle, these differences found in obstetric outcomes between fresh and FET should be taken into account. The adverse obstetric outcomes after FET found in this study emphasize that the freeze-all policy should not be offered to all the patients, but should be offered to those with a clear indication of the benefit of this strategy.

Fresh versus frozen embryo transfer for full-term singleton birth: a retrospective cohort study

Background

Improvements in vitrification and frozen embryo transfer (FET) technologies have rapidly increased, and some evidence suggests that FET may increase pregnancy rates and lead to more favourable perinatal outcomes. However, the outcome of interest should be offspring safety. Therefore, the primary objective of our study was to investigate whether FET was preferable to fresh embryo transfer (ET) in terms of full-term neonatal birthweight and congenital malformations.

Methods

This was a retrospective cohort study of patients with no pregnancy-related complications who underwent first fresh ETs (n = 2059) or FETs (n = 2053), resulting in full-term singletons births. Outcome measures were neonatal birthweight, low birthweight (LBW), small-for-gestational age (SGA), large-for-gestational age (LGA), macrosomia and congenital malformations. Additionally, we used logistic regression to adjust for baseline characteristics (age, BMI, No. of embryos transferred and embryo stage) between the two groups.

Results

The mean neonatal birthweight was higher for singletons born after FET than for singletons born after fresh ET (3468.7 ± 475.3 vs. 3386.7 ± 448.1; p < 0.001). The frequencies of full-term singleton LBW and SGA after FET were significantly lower than those after fresh ET (1.7% vs. 3.0 and 4.4% vs. 6.7%, respectively), with adjusted rate ratios of 0.59 (95% CI, 0.37 to 0.98; p = 0.026) and 0.73 (95% CI, 0.55 to 0.99; p = 0.041), respectively. FET resulted in higher frequencies of macrosomia and LGA (15.1% vs 10.2 and 22.8% vs. 17.5%, respectively) than fresh ET, with adjusted rate ratios of 1.43 (95% CI, 1.16 to 1.75; p = 0.001) and 1.26 (95% CI, 1.07 to 1.49; p = 0.007), respectively. Furthermore, the incidence of congenital malformations was not different between the two groups (1.2% vs. 0.9%), with a rate ratio of 0.288.

Conclusions

After the cycles with pregnancy-related complications were excluded and after adjustments for baseline characteristics, women undergoing FET were associated with a higher neonatal birthweight than women undergoing fresh ET cycles. Additionally, the FET protocol was associated with lower rates of LBW and SGA and higher rates of macrosomia and LGA than the fresh ET protocol. Meanwhile, no difference in the congenital malformation rate was evident between the two groups.

Postnatal persistence of fetal cardiovascular remodelling associated with assisted reproductive technologies: a cohort study

OBJECTIVE

To assess the postnatal persistence of fetal cardiovascular remodelling associated with assisted reproductive technologies (ART) in children at 3 years of age.

DESIGN

A cohort study of children conceived by ART.

SETTING

Maternal-Fetal Medicine Unit, Hospital Clinic Barcelona, Spain.

POPULATION SAMPLE

Eighty singleton pregnancies conceived by ART and 80 spontaneously conceived (controls) followed from fetal life up to childhood.

METHODS

Cardiovascular evaluation was performed at 3 years of corrected age, including echocardiography, carotid intima-media (cIMT) by ultrasound, and blood pressure.

MAIN OUTCOME MEASURES

Postnatal persistence of cardiovascular changes in children conceived by ART.

RESULTS

Compared with controls, children conceived by ART showed larger atria (right atrial area: control 4.9 cm² (0.9) versus ART 5.5 cm² (0.9), P < 0.001), more globular ventricles (right ventricular sphericity index: control mean 1.8 (SD 0.5) versus ART 1.6 (0.2), P < 0.001), and signs of systolic (tricuspid annular plane systolic excursion: control 18 mm (2) versus ART 16 mm (3), P < 0.001) and diastolic dysfunction (isovolumic relaxation time: control 68 ms (12) versus ART 79 ms (12), P < 0.001). ART children also presented increased systolic blood pressure (control 90 mmHg (6) versus ART 94 mmHg (5), P < 0.003) and cIMT (control 0.52 μm (0.14) versus ART 0.60 μm (0.16), P < 0.001) as compared with those spontaneously conceived.

CONCLUSIONS

Cardiovascular changes previously reported in ART fetuses persist postnatally at 3 years of age. These results underscore the importance of future studies for assessing the long-term cardiovascular health associated with ART.

TWEETABLE ABSTRACT

Cardiovascular changes described in fetuses conceived by ART, persist in children at 3 years of age.

Is frozen embryo transfer better for mothers and babies? Can cumulative meta-analysis provide a definitive answer?

BACKGROUND

Initial observational studies and a systematic review published 5 years ago have suggested that obstetric and perinatal outcomes are better in offspring conceived following frozen rather than fresh embryo transfers, with reduced risks of preterm birth, small for gestational age, low birth weight and pre-eclampsia. More recent primary studies are beginning to challenge some of these findings. We therefore conducted an updated systematic review and cumulative meta-analysis to examine if these results have remained consistent over time.

OBJECTIVE AND RATIONALE

The aim of this study was to perform a systematic review and cumulative meta-analysis (trend with time) of obstetric and perinatal complications in singleton pregnancies following the transfer of frozen thawed and fresh embryos generated through in-vitro fertilisation.

SEARCH METHODS

Data Sources from Medline, EMBASE, Cochrane Central Register of Clinical Trials DARE and CINAHL (1984-2016) were searched using appropriate key words. Observational and randomised studies comparing obstetric and perinatal outcomes in singleton pregnancies conceived through IVF using either fresh or frozen thawed embryos. Two independent reviewers extracted data in 2 × 2 tables and assessed the methodological quality of the relevant studies using CASP scoring. Both aggregated as well as cumulative meta-analysis was done using STATA.

OUTCOMES

Twenty-six studies met the inclusion criteria. Singleton babies conceived from frozen thawed embryos were at lower relative risk (RR) of preterm delivery (0.90; 95% CI 0.84-0.97) low birth weight (0.72; 95% CI 0.67-0.77) and small for gestational age (0.61; 95% CI 0.56-0.67) compared to those conceived from fresh embryo transfers, but faced an increased risk (RR) of hypertensive disorders of pregnancy (1.29; 95% CI 1.07-1.56) large for gestational age (1.54; 95% CI 1.48-1.61) and high birth weight (1.85; 95% CI 1.46-2.33). There was no difference in the risk of congenital anomalies and perinatal mortality between the two groups. The direction and magnitude of effect for these outcomes have remained virtually unchanged over time while the degree of precision has improved with the addition of data from newer studies.

WIDER IMPLICATIONS

The results of this cumulative meta-analysis confirm that the decreased risks of small for gestational age, low birth weight and preterm delivery and increased risks of large for gestational age and high birth weight associated with pregnancies conceived from frozen embryos have been consistent in terms of direction and magnitude of effect over several years, with increasing precision around the point estimates. Replication in a number of different populations has provided external validity for the results, for outcomes of birth weight and preterm delivery. Meanwhile, caution should be exercised about embarking on a policy of electively freezing all embryos in IVF as there are increased risks for large for gestational age babies and hypertensive disorders of pregnancy. Therefore, elective freezing should ideally be undertaken in specific cases such as ovarian hyperstimulation syndrome, fertility preservation or in the context of randomised trials.

IVF Transfer of Fresh or Frozen Embryos in Women without Polycystic Ovaries

BACKGROUND

Among women who are undergoing in vitro fertilization (IVF), the transfer of frozen embryos has been shown to result in a higher rate of live birth than the transfer of fresh embryos in those with infertility associated with the polycystic ovary syndrome. It is not known whether frozen-embryo transfer results in similar benefit in women with infertility that is not associated with the polycystic ovary syndrome.

METHODS

We randomly assigned 782 infertile women without the polycystic ovary syndrome who were undergoing a first or second IVF cycle to receive either a frozen embryo or a fresh embryo on day 3. In the frozen-embryo group, all grade 1 and 2 embryos had been cryopreserved, and a maximum of two embryos were thawed on the day of transfer in the following cycle. In the fresh-embryo group, a maximum of two fresh embryos were transferred in the stimulated cycle. The primary outcome was ongoing pregnancy after the first embryo transfer.

RESULTS

After the first completed cycle, ongoing pregnancy occurred in 142 of 391 women (36.3%) in the frozen-embryo group and in 135 of 391 (34.5%) in the fresh-embryo group (risk ratio in the frozen-embryo group, 1.05; 95% confidence interval [CI], 0.87 to 1.27; P=0.65). Rates of live birth after the first transfer were 33.8% and 31.5%, respectively (risk ratio, 1.07; 95% CI, 0.88 to 1.31).

CONCLUSIONS

Among infertile women without the polycystic ovary syndrome who were undergoing IVF, the transfer of frozen embryos did not result in significantly higher rates of ongoing pregnancy or live birth than the transfer of fresh embryos. (Funded by My Duc Hospital; ClinicalTrials.gov number, NCT02471573 .).

Frozen embryo transfer: a review on the optimal endometrial preparation and timing

STUDY QUESTION

What is the optimal endometrial preparation protocol for a frozen embryo transfer (FET)?

SUMMARY ANSWER

Although the optimal endometrial preparation protocol for FET needs further research and is yet to be determined, we propose a standardized timing strategy based on the current available evidence which could assist in the harmonization and comparability of clinic practice and future trials.

WHAT IS KNOWN ALREADY

Amid a continuous increase in the number of FET cycles, determining the optimal endometrial preparation protocol has become paramount to maximize ART success. In current daily practice, different FET preparation methods and timing strategies are used.

STUDY DESIGN, SIZE, DURATION

This is a review of the current literature on FET preparation methods, with special attention to the timing of the embryo transfer.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Literature on the topic was retrieved in PubMed and references from relevant articles were investigated until June 2017.

MAIN RESULTS AND THE ROLE OF CHANCE

The number of high quality randomized controlled trials (RCTs) is scarce and, hence, the evidence for the best protocol for FET is poor. Future research should compare both the pregnancy and neonatal outcomes between HRT and true natural cycle (NC) FET. In terms of embryo transfer timing, we propose to start progesterone intake on the theoretical day of oocyte retrieval in HRT and to perform blastocyst transfer at hCG + 7 or LH + 6 in modified or true NC, respectively.

LIMITATIONS REASONS FOR CAUTION

As only a few high quality RCTs on the optimal preparation for FET are available in the existing literature, no definitive conclusion for benefit of one protocol over the other can be drawn so far.

WIDER IMPLICATIONS OF THE FINDINGS

Caution when using HRT for FET is warranted since the rate of early pregnancy loss is alarmingly high in some reports.

STUDY FUNDING/COMPETING INTEREST(S)

S.M. is funded by the Research Fund of Flanders (FWO). H.T. and C.B. report grants from Merck, Goodlife, Besins and Abbott during the conduct of the study.

TRIAL REGISTRATION NUMBER

Not applicable.

Neonatal outcomes and congenital malformations in children born after human menopausal gonadotropin and medroxyprogesterone acetate treatment cycles

PURPOSE

To investigate neonatal outcomes and congenital malformations in children born after in vitro fertilization (IVF) and vitrified embryo transfer cycles using human menopausal gonadotrophin and medroxyprogesterone acetate (hMG + MPA) treatment.

METHODS

We performed a retrospective cohort study including 4596 live born babies. During January 2014-June 2016, children born after either hMG + MPA treatment, gonadotropin releasing hormone agonist short protocol, or mild ovarian stimulation were included. The main outcome measures were neonatal outcomes and congenital malformations.

RESULTS

Neonatal outcomes both for singletons and twins such as mean birth weight and length, gestational age, the frequency of preterm birth were comparable between groups. Rate of stillbirth and perinatal death were also similar. No significant differences were found in the overall incidence of congenital malformations between the three groups. Multivariable logistic regression indicated that hMG + MPA regimen did not significantly increase the risk of congenital malformations compared with short protocol and mild ovarian stimulation, with adjusted odds ratio of 1.22 [95% confidence interval (CI) 0.61-2.44] and 1.38 (CI 0.65-2.93), respectively, after adjusting for confounding factors.

CONCLUSIONS

Our data suggested that compared with conventional ovarian stimulations, hMG + MPA treatment neither compromised neonatal outcomes of IVF newborns, nor did increase the prevalence of congenital malformations.

Pregnancy and birth outcomes in couples with infertility with and without assisted reproductive technology: with an emphasis on US population-based studies

Infertility, defined as the inability to conceive within 1 year of unprotected intercourse, affects an estimated 80 million individuals worldwide, or 10-15% of couples of reproductive age. Assisted reproductive technology includes all infertility treatments to achieve conception; in vitro fertilization is the process by which an oocyte is fertilized by semen outside the body; non-in vitro fertilization assisted reproductive technology treatments include ovulation induction, artificial insemination, and intrauterine insemination. Use of assisted reproductive technology has risen steadily in the United States during the past 2 decades due to several reasons, including childbearing at older maternal ages and increasing insurance coverage. The number of in vitro fertilization cycles in the United States has nearly doubled from 2000 through 2013 and currently 1.7% of all live births in the United States are the result of this technology. Since the birth of the first child from in vitro fertilization >35 years ago, >5 million babies have been born from in vitro fertilization, half within the past 6 years. It is estimated that 1% of singletons, 19% of twins, and 25% of triplet or higher multiples are due to in vitro fertilization, and 4%, 21%, and 52%, respectively, are due to non-in vitro fertilization assisted reproductive technology. Higher plurality at birth results in a >10-fold increase in the risks for prematurity and low birthweight in twins vs singletons (adjusted odds ratio, 11.84; 95% confidence interval, 10.56-13.27 and adjusted odds ratio, 10.68; 95% confidence interval, 9.45-12.08, respectively). The use of donor oocytes is associated with increased risks for pregnancy-induced hypertension (adjusted odds ratio, 1.43; 95% confidence interval, 1.14-1.78) and prematurity (adjusted odds ratio, 1.43; 95% confidence interval, 1.11-1.83). The use of thawed embryos is associated with higher risks for pregnancy-induced hypertension (adjusted odds ratio, 1.30; 95% confidence interval, 1.08-1.57) and large-for-gestation birthweight (adjusted odds ratio, 1.74; 95% confidence interval, 1.45-2.08). Among singletons, in vitro fertilization is associated with increased risk of severe maternal morbidity compared with fertile deliveries (vaginal: adjusted odds ratio, 2.27; 95% confidence interval, 1.78-2.88; cesarean: adjusted odds ratio, 1.67; 95% confidence interval, 1.40-1.98, respectively) and subfertile deliveries (vaginal: adjusted odds ratio, 1.97; 95% confidence interval, 1.30-3.00; cesarean: adjusted odds ratio, 1.75; 95% confidence interval, 1.30-2.35, respectively). Among twins, cesarean in vitro fertilization deliveries have significantly greater severe maternal morbidity compared to cesarean fertile deliveries (adjusted odds ratio, 1.48; 95% confidence interval, 1.14-1.93). Subfertility, with or without in vitro fertilization or non-in vitro fertilization infertility treatments to achieve a pregnancy, is associated with increased risks of adverse maternal and perinatal outcomes. The major risk from in vitro fertilization treatments of multiple births (and the associated excess of perinatal morbidity) has been reduced over time, with fewer and better-quality embryos being transferred.

Evaluation of human embryo development in in vitro fertilization- and intracytoplasmic sperm injection-fertilized oocytes: A time-lapse study

Objective

We investigated whether the insemination method (in vitro fertilization [IVF] or intracytoplasmic sperm injection [ICSI]) affected morphokinetic events and abnormal cleavage events in embryonic development.

Methods

A total of 1,830 normal fertilized embryos were obtained from 272 IVF and ICSI cycles that underwent ovum retrieval culture using a time-lapse system (Embryoscope) from June 2013 to March 2015. All embryos were investigated by a detailed time-lapse analysis that measured the developmental events in the hours after IVF or ICSI insemination.

Results

No significant differences were observed between the two groups regarding clinical outcomes (p>0.05). ICSI-derived embryos showed significantly faster morphokinetics than those derived from conventional IVF, from the time to pronuclear fading to the time to 6 cells (p<0.05). However, no significant differences were found from the time to 7 cells to the time to expanded blastocyst (p>0.05). There were no differences in abnormal cleavage events between the two groups (p>0.05); they showed the same rates of direct cleavage from 1 to 3 cells, 2 multinucleated cells, 2 uneven cells, and reverse cleavage.

Conclusion

The morphokinetics of embryo development was found to vary between IVF- and ICSI-fertilized oocytes, at least until the 6-cell stage. However, these differences did not affect the clinical outcomes of the embryo. Additionally, no significant differences in abnormal cleavage events were found according to the fertilization method.

Retrospective comparative study of the factors affecting birthweights in frozen-thawed embryo transfer, compared to fresh embryo transfer

Aim

Several studies have indicated that the cause of the increased birthweight of frozen‐thawed embryos was associated with assisted reproductive technology (ART) procedures, such as cryopreservation. In the present study, the mean birthweight of singletons was compared between the ovulatory and hormone replacement therapy (HRT) cycles in order to investigate the primary factor that leads to higher birthweights from frozen‐thawed embryo transfer (FET).

Methods

This retrospective study was carried out from January 2011 to December 2014 on 2738 singletons who were born at 37‐41 weeks’ gestation, following ART in a single facility. The mean birthweight of the singletons who were born after a fresh embryo transfer (ET) was compared to the mean birthweight of the singletons who were born after a FET. In the FET cycles, the mean birthweight of the singletons was compared between the ovulatory and HRT cycles.

Results

The mean birthweight of the singletons who were born after a FET was significantly higher than that of the singletons who were born after a fresh ET. In the FET cycles, the birthweight from the HRT cycles was significantly higher than that from the ovulatory cycles. Among the HRT cycles, there was no difference between the birthweight of the singleton who were born from a blastocyst transfer and those who were born from a cleavage‐stage ET.

Conclusion

The primary factor to affect the birthweight of singletons might be the pre/postET hormonal environment of the endometrium and not the stage of the transferred embryo nor the frozen‐thawed procedure itself.

Fresh and Frozen-Thawed Embryo Transfer Compared to Natural Conception: Differences in Perinatal Outcome

BACKGROUND/AIM

To compare the pregnancy outcome of singletons conceived after transfer of cryopreserved and thawed embryos (frozen embryo transfer [FET]) to singletons conceived after fresh embryo transfer (fresh ET) and natural conceived singletons.

METHODS

Using a retrospective data analysis on a study population consisting of 1,261 singletons born after FET and 2,519 singletons born after fresh ET between 2006 and 2015. The control group consisted of singletons born after natural conception. Main outcome measures consisted of birth weight (in grams), gestational age, preterm birth (<37 weeks of gestation), being large for gestational age (LGA, above 90th weight percentile adjusted for gestational age) and Apgar scores.

RESULTS

Babies born after FET had an increased risk of high birth weight (adjusted OR [AOR]) 2.92; 1.503-3.482) and being LGA (AOR fresh ET vs. FET 1.47; 1.210-1.787) compared to singletons born after fresh ET, as well as higher birth weights compared to natural conceived children.

CONCLUSIONS

Singletons born after FET have a higher risk of high birth weight and being LGA compared to singletons after fresh ET and compared to natural conceived singletons. We assume that the freezing process might be the underlying cause.

Elevated progesterone and its impact on birth weight after fresh embryo transfers

PURPOSE

The purpose of the study was to examine the association between serum progesterone levels on the day of hCG administration and birth weight among singleton live births after fresh embryo transfer.

METHODS

This study was conducted as a retrospective cohort database analysis on patients who underwent IVF treatment cycles from January 2004 to April 2012. The study was performed at a University affiliated private infertility practice. All cycles that had achieved a singleton live birth after fresh embryo transfer and for which progesterone was measured on the day of hCG administration were examined. Generalized linear models were used to calculate mean birth weight and z-scores.

RESULTS

We analyzed 817 fresh IVF embryo transfers in which birth weight, gestational age, and progesterone (ng/mL) level on day of hCG administration were documented. While there was a decrease in birth weight as progesterone quartile [≤0.54; >0.54 to ≤0.81; >0.81 to ≤1.17; >1.17 ng/mL] increased, the difference in mean birth weights among the four quartiles was not statistically significant (p = 0.11) after adjusting for maternal age and peak estradiol levels. When dichotomizing based on a serum progesterone considered clinically elevated, cycles with progesterone >2.0 ng/mL had a significantly lower mean singleton birth weight (2860 g (95% CI 2642 g, 3079 g)) compared to cycles with progesterone ≤2.0 ng/mL (3167 g (95% CI 3122 g, 3211 g) p = 0.007)) after adjusting for maternal age and estradiol.

CONCLUSION

We demonstrated that caution should be exercised when performing fresh embryo transfers with elevated progesterone levels and in particular with levels (>2.0 ng/mL) as this may lead to lower birth weight.

No difference in congenital anomalies prevalence irrespective of insemination methods and freezing procedure: cohort study over fourteen years of an ART population in the south of France

PURPOSE

A retrospective cohort study was conducted to evaluate and compare the prevalence of congenital anomalies in babies and fetuses conceived after four procedures of assisted reproduction technologies (ART).

METHODS

The prevalence of congenital anomalies was compared retrospectively between 2750 babies and fetuses conceived between 2001 and 2014 in vitro fertilization with standard insemination (IVF), IVF with intracytoplasmic sperm injection (ICSI), IVF with frozen embryo transfer (FET-IVF), and ICSI with frozen embryo transfer (FET-ICSI). Congenital anomalies were described according to European Surveillance of Congenital Anomalies (EUROCAT) classification. The parental backgrounds, biologic parameters, obstetric parameters, and perinatal outcomes were compared between babies and fetuses with and without congenital anomalies. Data were analyzed by the generalized estimating equation.

RESULTS

Between 2001 and 2014, a total of 2477 evolutionary pregnancies were notified. Among these pregnancies, 2379 were included in the analysis. One hundred thirty-four babies and fetuses had a congenital anomaly (4.9%). The major prevalences found among the recorded anomalies were congenital heart defects, chromosomal anomalies, and urinary defects. However, the risk of congenital anomalies in babies and fetuses conceived after FET was not increased compared with babies and fetuses conceived after fresh embryo transfer, even when adjusted for confounding factors (p = 0.40).

CONCLUSIONS

There is no increased risk of congenital anomalies in babies and fetuses conceived by fresh versus frozen embryo transfer after in vitro fertilization with and without micromanipulation. Indeed, distribution of congenital anomalies found in our population is consistent with the high prevalence of congenital heart defects, chromosomal anomalies, and urinary defects that have been found by other authors in children conceived by infertile couples when compared to children conceived spontaneously.

Perinatal outcomes in children born after fresh or frozen embryo transfer: a Catalan cohort study based on 14,262 newborns

OBJECTIVE

To ascertain whether perinatal outcomes are affected by vitrification and/or controlled ovarian hyperstimulation (COH).

DESIGN

Register-based cohort study.

SETTING

Not applicable.

PATIENT(S)

Women undergoing in vitro fertilization (IVF) between 2008 and 2012 using autologous or donated eggs who had a singleton pregnancy delivered from the 24th week onward.

INTERVENTION(S)

Fresh embryo transfer (ET) or frozen-thawed ET in women undergoing IVF.

MAIN OUTCOME MEASURE(S)

Primary outcome birthweight, and secondary outcomes gestational age at delivery, small for gestational age, mode of delivery, and perinatal mortality.

RESULT(S)

In the autologous egg population, newborns from the fresh ET group had lower birthweight than the frozen-thawed ET group (3,152.9 ± 545.5g and 3,343.2 ± 532.3g, respectively), and this difference persisted even after adjusting for confounding factors, and the newborns had a higher risk of being small for gestational age (SGA). In contrast, among egg-donor recipients undergoing ET, the mean birthweight did not differ between the groups (3,165 ± 604.15 g and 3,143.60 ± 604.21g in the fresh and frozen-thawed ET groups, respectively); however, in the adjusted regression model birthweight was statistically significantly higher in the fresh ET group than the frozen-thawed ET group. The risk of SGA remained comparable between the fresh versus frozen-thawed ET groups. We observed no statistically significant differences in perinatal mortality between groups either in the autologous egg population or in the donor recipient group.

CONCLUSION(S)

Perinatal outcomes are negatively affected by COH and not affected by the vitrification process.