Cumulative live birth rate of a blastocyst versus cleavage stage embryo transfer policy during in vitro fertilisation in women with a good prognosis: multicentre randomised controlled trial

OBJECTIVES

To evaluate whether embryo transfers at blastocyst stage improve the cumulative live birth rate after oocyte retrieval, including both fresh and frozen-thawed transfers, and whether the risk of obstetric and perinatal complications is increased compared with cleavage stage embryo transfers during in vitro fertilisation (IVF) treatment.

DESIGN

Multicentre randomised controlled trial.

SETTING

21 hospitals and clinics in the Netherlands, 18 August 2018 to 17 December 2021.

PARTICIPANTS

1202 women with at least four embryos available on day 2 after oocyte retrieval were randomly assigned to either blastocyst stage embryo transfer (n=603) or cleavage stage embryo transfer (n=599).

INTERVENTIONS

In the blastocyst group and cleavage group, embryo transfers were performed on day 5 and day 3, respectively, after oocyte retrieval, followed by cryopreservation of surplus embryos. Analysis was on an intention-to-treat basis, with secondary analyses as per protocol.

MAIN OUTCOME MEASURES

The primary outcome was the cumulative live birth rate per oocyte retrieval, including results of all frozen-thawed embryo transfers within a year after randomisation. Secondary outcomes included cumulative rates of pregnancy, pregnancy loss, and live birth after fresh embryo transfer, number of embryo transfers needed, number of frozen embryos, and obstetric and perinatal outcomes.

RESULTS

The cumulative live birth rate did not differ between the blastocyst group and cleavage group (58.9% (355 of 603) v 58.4% (350 of 599; risk ratio 1.01, 95% confidence interval (CI) 0.84 to 1.22). The blastocyst group showed a higher live birth rate after fresh embryo transfer (1.26, 1.00 to 1.58), lower cumulative pregnancy loss rate (0.68, 0.51 to 0.89), and lower mean number of embryo transfers needed to result in a live birth (1.55 v 1.82; P<0.001). The incidence of moderate preterm birth (32 to <37 weeks) in singletons was higher in the blastocyst group (1.87, 1.05 to 3.34).

CONCLUSION

Blastocyst stage embryo transfers resulted in a similar cumulative live birth rate to cleavage stage embryo transfers in women with at least four embryos available during IVF treatment.

TRIAL REGISTRATION

International Clinical Trial Registry Platform NTR7034.

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.

The Effectiveness of Routine Cerclage in In Vitro Fertilization (IVF) Twins

INTRODUCTION

The incidence of twin pregnancies is on the rise worldwide due to assisted reproductive technologies. Cervical dilatation is a frequent complication and can be considered a cause of premature births in twin pregnancies. In vitro fertilization (IVF) twins are more prone to preterm delivery. Routine cervical cerclage with normal cervical length is not recommended in twins, but studies were not done on IVF twins. So, this study aims to evaluate the effectiveness of routine transvaginal cerclage in twin IVF pregnancies with normal cervical length on maternofetal outcome.

MATERIALS AND METHODS

A retrospective case-control study was conducted at a maternity hospital in eastern India from January 2016 to December 2019 with over 21800 deliveries. Two groups were taken, cases were those IVF twins with normal cervical length in whom cervical cerclage was done as they have referred to our hospital from the IVF centers for cerclage and in control no-cervical cerclage as they are referred from other IVF centers where cerclage was not a routine protocol. We have excluded cerclage done for history, ultrasound indicated, uterine anomalies, and monochorionic twins. Fifteen participants were recruited in both cases and controls.

RESULTS

In our study 2 (6.66%), 4 (13%), and 26 (86%) were IVF twins delivered at a gestational age of <28 weeks, 28-32 weeks, and 32-37 weeks, respectively. The mean age of participants, mean gestation age at delivery, and birth weight in cases and control were 35.27 ± 5.98 years (min: 23; max: 45), 32.40 ± 5.54 years (min: 25; max: 44); 34 weeks 2 days ± 3.28 (min: 31; max: 37), 33 weeks 5 days ± 1.66 (min: 25; max: 37); 1961.33 ± 340 gram, 1899.33 ± 437.48 gram, respectively with no statistical significant difference (p = 0.186, p = 1, p = 0.668, respectively) Conclusion: Routine transvaginal cerclage is not effective in twin IVF pregnancies with normal cervical length for preventing preterm births. IVF twin women usually present at a late age and their birth weight are also low.

Monochorionic-triamniotic triplet pregnancy following artificial reproductive technology: Report of a rare case in Taiwan

OBJECTIVE

Monochorionic-triamniotic (MCTA) triplet pregnancies following artificial reproductive technologies are uncommon. We report a case in which one of two transferred embryos differentiated into an MCTA triplet. This study aimed to investigate the potential factors contributing to MCTA triplet pregnancy.

CASE REPORT

A 39-year-old woman underwent her second frozen embryo transfer with hatching blastocysts, which resulted in the detection of an MCTA triplet on ultrasonography. She delivered by cesarean section at 32 weeks of gestation, resulting in the birth of three live male infants. Her medical history and in vitro fertilization treatment were reviewed to identify potential causes.

CONCLUSION

The etiology of MCTA triplet pregnancy remains multifactorial. In the presented case, prolonged in vitro culture to the blastocyst stage and inner cell mass splitting were potential contributing factors. Further research is needed to fully understand the complexity of MCTA triplet pregnancy.

Multiple Gestation after Elective Single-Embryo Transfer: A State-of-the-Art Review of Literature and Suggested Mechanisms

Background

Elective single-embryo transfers are being increasingly used to curb the increase in multiple gestation rates. However, it has been documented that single-embryo transfers could still result in twins and on rarer occasions in triplet pregnancies. Main Body. A literature review was done to highlight the possible mechanisms leading to embryonic splitting. In this review, the incidence of zygotic splitting was addressed and the notion of chorionicity was explained. Risk factors for zygotic splitting and suggested mechanisms for both twin and higher order pregnancies were suggested and discussed.

Conclusion

The hypotheses that we have so far remain unproven due to the rarity of zygotic splitting as well as the ethicolegal considerations of human embryo research. The presence of such incidents necessitates extensive counselling of the couple.

Septal Rupture During Early Pregnancy and Successful Delivery in Monozygotic Dichorionic Diamniotic Twin After a Single Blastocyst Transfer

The frequency of twins resulting from a single embryo transfer has been reported to be 1.56%, with the majority being monochorionic. We present a case of septal rupture at 8 weeks of gestation and successful delivery at 36 weeks of gestation of a monozygotic dichorionic diamniotic twin after a single blastocyst transfer. This report could partially clarify the pathogenesis of monozygotic twins and septal disruption. A 37-year-old woman with 9 months of primary infertility was referred to our department. After seven cycles of artificial insemination, she underwent her first in vitro fertilization. Ten cumulous-oocyte complexes were retrieved, of which three were fertilized, and three blastocysts were cryopreserved. The first single blastocyst transfer in a hormone replacement cycle resulted in a dichorionic diamniotic twin pregnancy. Transvaginal ultrasound at 7 weeks and 4 days gestation revealed a size difference in the gestational sacs and a disruption of the inter-amniotic membrane between the two gestational sacs at 8 weeks and 6 days. Both fetuses were seen in the larger gestational sac; however, the umbilical cord of the migrated fetus was from the original gestational sac. Both fetuses developed without discordancy or obvious anomalies. At 36 weeks and 6 days of gestation, the patient underwent cesarean delivery, resulting in the birth of two viable male infants without any congenital anomalies (weighing 2256 g and 2456 g). Two amniotic cavities existed; however, no chorionic villi were present. There have been many reports on septal disruption in monochorionic diamniotic twins; however, only two cases of dichorionic diamniotic twins have been reported. Furthermore, the onsets in both reports were after the second trimester of pregnancy. This report presents the first case of septal disruption in dichorionic diamniotic twins during the first trimester.

Management strategies following implantation failure of euploid embryos

Background

Euploid blastocyst implantation failure may result from embryonic factors undetectable by preimplantation genetic testing for aneuploidy (PGT-A); however, various nonembryonic factors can also intricately interfere with implantation. This review seeks to clarify evidence-based testing and treatments for implantation failure after euploid embryo transfer.

Methods

We conducted a review of the literature on implantation failure after euploid embryo transfer or multiple embryo transfer cycles, which mainly included systematic reviews and meta-analyses.

Results

The recommended tests for implantation failure include (1) hysteroscopy, (2) endometrial CD138 immunohistochemistry and bacterial culture, (3) serum 25-hydroxyvitamin D3, and (4) thrombophilia screening. Based on diagnostic findings, the following treatments have been recommended: (1) antibiotics for chronic endometritis, (2) vitamin D replacement, (3) lifestyle modification, and (4) low-dose aspirin starting from the postimplantation period for thrombophilia. Moreover, frozen-thawed single euploid blastocyst transfer using assisted hatching and hyaluronan-enriched transfer medium may support embryo implantation.

Conclusion

To ensure a successful pregnancy in subsequent embryo transfers, simple, inexpensive, and evidence-based tests and treatments should be selected.

Effect of blastocyst morphology on the incidence of monozygotic twinning pregnancy after single blastocyst transfer

Aims: To explore whether blastocyst morphology [blastocyst stage, inner cell mass (ICM), and trophectoderm (TE) grading] impacts the occurrence of monozygotic twinning (MZT) after single blastocyst transfer (SBT).Materials and methods: A single-center retrospective cohort study was conducted including all clinical pregnancies after single blastocyst transfer between January 2015 and September 2021 (n = 9229). Blastocyst morphology was assessed using Gardner grading system. MZT was defined as more than one gestational sac (GS), or two or more fetal heartbeats in a single GS via ultrasound at 5-6 gestational weeks.Results: The overall MZT rate was 2.46% (227 of 9229 cases), of which was the highest in blastocysts of grade A TE and lowest in those with grade C TE (grade A: B:C = 3.40%:2.67%:1.58%, p = .002). Higher risk of MZT pregnancy was associated with higher trophectoderm grading [A vs. C: aOR, 1.883, 95% CI 1.069-3.315, p = .028; B vs C: aOR, 1.559, 95% CI 1.066-2.279, p = .022], but not extended culture in vitro (day 5 vs. day 6), vitrification (fresh vs. frozen-thawed ET), assisted hatching (AH), blastocyst stage (stage 1-6) or ICM grading (A vs. B).Conclusions: We conclude that TE grade is an independent risk factor of MZT after single blastocyst transfer. Blastocysts with high-grade trophectoderm are more liable to obtain monozygotic multiple gestation.

A multicentre double-blinded randomized controlled trial on the efficacy of laser-assisted hatching in patients with repeated implantation failure undergoing IVF or ICSI

STUDY QUESTION

Does assisted hatching increase the cumulative live birth rate in subfertile couples with repeated implantation failure?

SUMMARY ANSWER

This study showed no evidence of effect for assisted hatching as an add-on in subfertile couples with repeated implantation failure.

WHAT IS KNOWN ALREADY

The efficacy of assisted hatching, with regard to the live birth rate has not been convincingly demonstrated in randomized trials nor meta-analyses. It is suggested though that especially poor prognosis women, e.g. women with repeated implantation failure, might benefit most from assisted hatching.

STUDY DESIGN, SIZE, DURATION

The study was designed as a double-blinded, multicentre randomized controlled superiority trial. In order to demonstrate a statistically significant absolute increase in live birth rate of 10% after assisted hatching, 294 participants needed to be included per treatment arm, being a total of 588 subfertile couples. Participants were included and randomized from November 2012 until November 2017, 297 were allocated to the assisted hatching arm of the study and 295 to the control arm. Block randomization in blocks of 20 participants was applied and randomization was concealed from participants, treating physicians, and laboratory staff involved in the embryo transfer procedure. Ovarian hyperstimulation, oocyte retrieval, laboratory procedures, embryo selection for transfer and cryopreservation, the transfer itself, and luteal support were performed according to local protocols and were identical in both the intervention and control arm of the study with the exception of the assisted hatching procedure which was only performed in the intervention group. The laboratory staff performing the assisted hatching procedure was not involved in the embryo transfer itself.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were eligible for inclusion in the study after having had either at least two consecutive fresh IVF or ICSI embryo transfers, including the transfer of frozen and thawed embryos originating from those fresh cycles, and which did not result in a pregnancy or as having had at least one fresh IVF or ICSI transfer and at least two frozen embryo transfers with embryos originating from that fresh cycle which did not result in a pregnancy. The study was performed at the laboratory sites of three tertiary referral hospitals and two university medical centres in the Netherlands.

MAIN RESULTS AND THE ROLE OF CHANCE

The cumulative live birth rate per started cycle, including the transfer of fresh and subsequent frozen/thawed embryos if applicable, resulted in 77 live births in the assisted hatching group (n = 297, 25.9%) and 68 live births in the control group (n = 295, 23.1%). This proved to be statistically not significantly different (relative risk: 1.125, 95% CI: 0.847 to 1.494, P = 0.416).

LIMITATIONS, REASONS FOR CAUTION

There was a small cohort of subfertile couples that after not achieving an ongoing pregnancy, still had cryopreserved embryos in storage at the endpoint of the trial, i.e. 1 year after the last randomization. It cannot be excluded that the future transfer of these frozen/thawed embryos increases the cumulative live birth rate in either or both study arms. Next, at the start of this study, there was no international consensus on the definition of repeated implantation failure. Therefore, it cannot be excluded that assisted hatching might be effective in higher order repeated implantation failures.

WIDER IMPLICATIONS OF THE FINDINGS

This study demonstrated no evidence of a statistically significant effect for assisted hatching by increasing live birth rates in subfertile couples with repeated implantation failure, i.e. the couples which, based on meta-analyses, are suggested to benefit most from assisted hatching. It is therefore suggested that assisted hatching should only be offered if information on the absence of evidence of effect is provided, at no extra costs and preferably only in the setting of a clinical trial taking cost-effectiveness into account.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

Netherlands Trial Register (NTR 3387, NL 3235, https://www.clinicaltrialregister.nl/nl/trial/26138).

TRIAL REGISTRATION DATE

6 April 2012.

DATE OF FIRST PATIENT’S ENROLMENT

28 November 2012.

Risk factors associated with monozygotic twinning in offspring conceived by assisted reproductive technology

STUDY QUESTION

What are the factors influencing the occurrence of monozygotic (MZ) twins in offspring conceived by assisted reproductive technology (ART)?

SUMMARY ANSWER

Parental ages, the transfer of fresh versus frozen embryos, and the grade of blastocysts are all related to MZ twinning in ART offspring.

WHAT IS KNOWN ALREADY

Offspring conceived by ART have significantly increased risk of MZ twins, which may be due to the characteristics of the infertile population. The objective of this study was to explore the incidence of monozygotic (MZ) twins after ART and to clarify the risk factors for MZ twinning.

STUDY DESIGN SIZE DURATION

A total of 255 monozygotic twins were enrolled in this cohort study, and then matched with singletons at a ratio of 1:4 randomly (with 1020 in the control group). All offspring were conceived by single embryo transfer.

PARTICIPANTS/MATERIALS SETTING METHODS

The collected data were divided into the following three aspects for analysis: characteristics of the infertile population, gamete or embryo manipulations, and factors related to embryo development.

MAIN RESULTS AND THE ROLE OF CHANCE

The incidence of MZ twins was 1.638% (255 out of 15 567 pregnancies after single embryo transfers). Compared to singleton births, a significantly lower rate of frozen embryo transfers (FET; 78.0% vs 86.1% P = 0.002) was seen amongst the MZ twins. Amongst fresh ETs, the rate of blastocyst transfers in the MZ twins group was higher compared to that in the control group (92.9% vs 75.4%, P = 0.005). We also found that certain grades of blastocysts in terms of trophectoderm (TE) development, inner cell mass + TE development and the classification of 'top-quality' embryos were associated with the incidence of MZ twinning (P = 0.025, P = 0.012, P = 0.020, respectively). Logistic regression analysis revealed that higher paternal age (odds ratio (OR) = 0.94, 95% CI = 0.89-1.00, P = 0.029) and FET (OR = 0.48, 95% CI = 0.33-0.68, P = 0.001) may be protective factors against MZ twinning. However, higher maternal age (OR = 1.07, 95% CI = 1.01-1.13, P = 0.027) and the transfer of blastocysts (OR = 4.31, 95% CI = 1.46-12.73, P = 0.008) appeared to be associated with an increased risk of MZ twinning. Amongst blastocyst transfers, a C grade TE may be protective factor against MZ twinning (B: OR = 1.90, 95% CI = 1.18-3.07, P = 0.009; A: OR = 1.58, 95% CI = 0.93-2.67, P = 0.089).

LIMITATIONS REASONS FOR CAUTION

First, our definition of MZ twins was based on twins' birth after single embryo transfers (SET), rather than ultrasound examination during early pregnancy. Second, the parental characteristics of the two groups were homogenous, so it was difficult to find any associations between infertility factors and the incidence of MZ twins.

WIDER IMPLICATIONS OF THE FINDINGS

This multifaceted analysis of the risk factors for MZ twinning provides some information for clinical interventions in high-risk populations.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the National Key Technology Research and Developmental Program of China (2022YFC2704404), CAMS Innovation Fund for Medical Sciences (2021-I2M-5-001), Taishan Scholars Program for Young Experts of Shandong Province (tsqn201909195), the Basic Science Center Program (31988101), and the Shandong Provincial Key Research and Development Program (2020ZLYS02). All authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Current Status and Issues of the Japan Oncofertility Registry

Purpose: Fertility preservation (FP) is becoming increasingly common among child, adolescent, and young-adult (CAYA) patients with cancer. However, Japan has long lacked definite estimates of utilization rates for FP services among CAYA patients with cancer, and little is known about disease/FP outcomes among users. Therefore, the Japan Society for Fertility Preservation (JSFP) launched the Japan Oncofertility Registry (JOFR) in 2018 and started the online registration of information regarding primary disease, FP, and data on prognosis and pregnancy outcomes. This study reports the analytical results of FP data registered in the JOFR as of 2021. Methods: Data about patients' primary disease(s), treatment courses, cancer and pregnancy outcomes, and specific procedures were extracted from the JOFR and analyzed. Results: In 2021, 1244 patients received counseling or treatment related to FP (540 males, 704 females). While the numbers of males in each age group were approximately equal, most females were aged between 31 and 40 years. In total, 490 male and 540 female patients underwent FP procedures. Leukemia, testicular cancer, and malignant lymphoma accounted for the majority of male cases seeking treatment, whereas breast cancer was the primary disease in two-thirds of the females. Since 1999, 395 patients have accumulatively experienced subsequent pregnancy. Conclusions: As of January 2022, >7000 cases from >100 fertility facilities have been registered in the JOFR. In the future, maintaining JOFR to disseminate information on cancer prognoses, pregnancy rates, and other oncofertility outcomes is expected to drive further expansion of oncofertility services in Japan.

Assisted Reproduction and Discussion of Rare Cases in Monozygotic Twinning

Assisted reproductive technology is a crucial factor that increases the incidence of monozygotic twinning in humans. This article discusses the impact of various indicators in assisted reproductive technology studies on pregnancy outcomes, especially studies with a large number of clinical cases. Furthermore, three rare cases in multiples pregnancy are discussed: fetus papyraceous of a pair of male monozygotic twins in a set of triplets, two pairs of sesquizygotic twins with sex-discordance, and rare conjoined triplets.

Recurrence risk and risk factors for monozygotic twin and triplet birth in over 65,000 single-embryo transfers

PURPOSE

To determine the recurrence risk and risk factors for monozygotic splitting after elective single-embryo transfers (eSET).

METHODS

A retrospective cohort study was performed investigating 65,664 eSET cycles that resulted in a clinical pregnancy as reported in the Society for Assisted Reproductive Technology (SART) Clinical Outcomes Reporting System (CORS) between 2004 and 2017. Monozygosity was defined as more than one fetal heart tone by the first-trimester ultrasound and concordant sex at live birth. The primary outcome was recurrence risk, with recurrence defined as one patient having two or more cycles of eSET resulting in monozygotic multiples. The secondary objective was to identify factors associated with smonozygotic splitting, using a multivariable logistic regression model and a stepwise purposeful model selection.

RESULTS

There were 1355 (2.05%) pregnancies that resulted in two or more fetal heart tones after SET, including 840 monozygotic twins and triplets at birth. Recurrence occurred in two cases-0.0001% of patients with multiple eSET cycles. One case resulted from embryos created from a single cohort with intracytoplasmic sperm injection (ICSI), assisted hatching (AH), and blastocyst transfers. The second case resulted from donor egg embryos with ICSI and blastocyst transfers. Risk factors associated with monozygotic live birth were blastocyst transfer (OR 1.23, 95% CI 1.04-1.47, P = 0.0176) and AH (OR 1.23, 95% CI 1.05-1.44, P = 0.0081).

CONCLUSION

Recurrence of monozygotic live births in eSET was very rare. Blastocyst transfer and AH were confirmed to be risk factors for monozygotic live births, while ICSI, PGT, and FET do not appear to be associated.

Odds and Predictors of Monozygotic Twinning in a Multicentre Cohort of 25,794 IVF Cycles

The rate of monozygotic twinning (MZT) has seen a gradual increase in recent years. Numerous parameters involved in ART procedures are blamed for this surge, even though the exact explanation is as yet unknown. Our study's objectives were to determine the risk variables for monozygotic twinning after ART and to estimate their prevalence. We examined 25,794 IVF cycles for the incidence of monozygotic twinning in this observational analysis. Our study, which was carried out across seven tertiary IVF centres over the course of four years, found an overall MZT rate of 0.37% per embryo transfer procedure and 0.88% of all pregnancies. Monozygotic twinning was more commonly seen in fresh single-embryo transfer (SET) and blastocyst transfer cycles. Larger multicentre studies are needed to explore the potential risk variables.

Growth of twins conceived using assisted reproductive treatments up to 5 years old: a national growth cohort

STUDY QUESTION

Do twins conceived through assisted reproductive treatments (ART) grow differently from naturally conceived (NC) twins in early life?

SUMMARY ANSWER

Assessments at 6-8 weeks old and at school entry show that ART twins conceived from frozen embryo transfer (FET) grow faster than both NC twins and ART twins conceived from fresh embryo transfer (ET).

WHAT IS KNOWN ALREADY

Singletons born from fresh ET 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. Evidence on early child growth of ART twins relative to NC twins is inconsistent; most studies are small and do not distinguish FET from fresh ET cycles.

STUDY DESIGN, SIZE, DURATION

This cohort study included 13 528 live-born twin babies conceived by ART (fresh ET: 2792, FET: 556) and NC (10 180) between 1991 and 2009 in Scotland. The data were obtained by linking Human Fertilisation and Embryology Authority ART register data to the Scottish Morbidity Record (SMR02) and Scottish child health programme datasets. Outcome data were collected at birth, 6-8 weeks (first assessment), and school entry (4-7 years old) assessments. The primary outcome was growth, measured by weight at the three assessment points. Secondary outcomes were length (at birth and 6-8 weeks) or height (at school entry), BMI, occipital circumference, gestational age at birth, newborn intensive care unit admission, and growth rates (between birth and 6-8 weeks and between 6-8 weeks and school entry).

PARTICIPANTS/MATERIALS, SETTING, METHODS

All twins in the linked dataset (born between 1991 and 2009) with growth data were included in the analysis. To determine outcome differences between fresh ET, FET, and NC twins, linear mixed models (or analogous logistic regression models) were used to explore the outcomes of interest. All models were adjusted for available confounders: gestational age/child age, gender, maternal age and smoking, Scottish Index of Multiple Deprivation, year of treatment, parity, ICSI, and ET stage.

MAIN RESULTS AND THE ROLE OF CHANCE

In the primary birth weight models, the average birth weight of fresh ET twins was lower [-35 g; 95% CI: (-53, -16)g] than NC controls, while FET twins were heavier [71 g; 95% CI (33, 110) g] than NC controls and heavier [106 g; 95% CI (65, 146) g] than fresh ET twins. However, the difference between FET and NC twins was not significant when considering only full-term twins (≥37 weeks gestation) [26 g; 95% CI (-30, 82) g], while it was significantly higher in preterm twins [126 g; 95% CI (73, 179) g]. Growth rates did not differ significantly for the three groups from birth to 6-8 weeks. However, FET twins grew significantly faster from 6 to 8 weeks than NC (by 2.2 g/week) and fresh ET twins (by 2.1 g/week). By school entry, FET twins were 614 g [95% CI (158, 1070) g] and 581 g [95% CI (100, 1063) g] heavier than NC and fresh ET twins, respectively. Length/height and occipital frontal circumference did not differ significantly at any time point.

LIMITATIONS, REASONS FOR CAUTION

Although the differences between ART and NC reflect the true ART effects, these effects are likely to be mediated partly through the different prevalence of mono/dizygotic twins in the two groups. We could not explore the mediating effect of zygosity due to the unavailability of data. The confounding variables included in the study were limited to those available in the datasets.

WIDER IMPLICATIONS OF THE FINDINGS

Live-born twins from FET cycles are heavier at birth, grow faster than their fresh ET and NC counterparts, and are still heavier at school entry. This differs from that observed in singletons from the same cohort, where babies in the three conception groups had similar weights by school entry age. The results are reassuring on known differences in FET versus fresh ET and NC twin outcomes. However, FET twins grow faster and are consistently larger, and more ART twins depict catch-up growth. These may lead to an increased risk profile for non-communicable diseases in later life. As such, these twin outcomes require careful evaluation using more recent and comprehensive cohorts.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the EU H2020 Marie Sklodowska-Curie Innovative Training Networks (ITN) grant Dohartnet (H2020-MSCA-ITN-2018-812660). The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

Outcomes and cost analysis of single-embryo transfer versus double-embryo transfer

BACKGROUND

Studies had compared single-embryo transfer to double-embryo transfer with cleavage stage embryos and found that while single-embryo transfer was less costly, it was also associated with a lower live birth rate than double-embryo transfer. A single blastocyst transfer has been shown to improve the live birth rate per cycle compared to single-embryo transfer at cleavage stage.

OBJECTIVES

To compare live birth rates and real costs of elective single-embryo transfer to double-embryo transfer and to determine the incremental cost-effectiveness ratio of these two strategies in an unselected pool of women in a single center.

DESIGN

Retrospective study.

METHODS

We analyzed data of 4232 women who underwent their first fresh in vitro fertilization/intra-cytoplasmic sperm injection cycles with at least two embryos available for transfer in KK Women's and Children's Hospital from 2010 to 2017.

RESULTS

Five hundred and sixty-four women underwent elective single-embryo transfer and 3668 women underwent double-embryo transfer. One hundred and fifty-six women who failed to achieve a live birth in their fresh elective single-embryo transfer cycle underwent a sequential thaw single-embryo transfer cycle. Live birth rate of fresh elective single-embryo transfer was significantly higher at 41.3% than that of double-embryo transfer at 32.6%. Cumulative live birth rate for sequential elective single-embryo transfer (fresh elective single-embryo transfer + thaw single-embryo transfer) was 47.9%. After accounting for variables which may affect live birth rates such as age and stage of embryo transfer, the odds of achieving a live birth from double-embryo transfer was 24% lower than that from sequential single-embryo transfer, although not statistically significant. For every live birth gained from an elective single-embryo transfer compared to double-embryo transfer, cost savings were S$20,172 per woman. If a woman had to have a sequential single-embryo transfer after a failed single-embryo transfer in her fresh cycle, cost savings were reduced to S$1476 per woman.

CONCLUSION

Single-embryo transfer is a dominant strategy in an unselected population and adopting it in assisted reproductive treatments (ART) can produce cost savings without compromising on live birth rates.

Molecular Characterization of a Rare Case of Monozygotic Dichorionic Diamniotic Twin Pregnancy after Single Blastocyst Transfer in Preimplantation Genetic Testing (PGT)

Preimplantation genetic testing (PGT) is widely used to select unaffected embryos, increasing the odds of having a healthy baby. During the last few decades, it was accepted that monozygotic dichorionic diamniotic twin pregnancies occurred from the embryo splitting before Day 3 postfertilization according to Corner's dogma. Hence, the occurrence of a dichorionic diamniotic twin pregnancy after a single blastocyst transfer was considered a dizygotic pregnancy resulting from blastocyst transfer and concurrent natural fertilization. In our study, we have provided for the first time molecular proof that a single blastocyst transfer can result in a monozygotic dichorionic diamniotic twin pregnancy, invalidating Corner's dogma. In this case, we recommend systematically assessing the genetic status of dichorionic twins after single blastocyst transfer using prenatal diagnosis to exclude the risk from a potential concurrent spontaneous pregnancy and to ensure that both fetuses are unaffected. To achieve this goal, we have developed here an innovative noninvasive prenatal diagnosis by exclusion of paternal variants with droplet digital PCR, maximizing the reliability of genetic diagnosis. Further multicentric prospective studies using genetic testing are now required to establish the rate of blastocyst splitting leading to dichorionic pregnancy in PGT and to identify the risk factors.

Birth weight reference for Japanese twins and risk factors for infant mortality: A population-based study

There is no standard birth weight curve for twins in Japan other than a prototype curve based on 1988–1991. Twins have a high perinatal mortality rate than singletons; therefore, we developed a new standard curve for twin birth weight using data from the 1995–2016 Vital Statistics and compared it with previous reports. We used 469,064 cases for analysis, excluding stillbirths and cases with missing values, and created a standard curve using LMS (statistical methods to vary the distribution by using skewness, median, and coefficient of variation) method. In comparison with previous reports, the mean birth weight decreased by 100–200 g. The groups with the lowest neonatal death rates (NDRs) and infant death rates (IDRs) were those with a birth weight of 1,500–2,499 g (NDR: 0.3%, IDR: 0.6%) and those born at 34–36 weeks (NDR: 0.2%, IDR: 0.4%). Compared to these, the IDR was significantly higher in the 2,500–3,999 g group and the 37–39 weeks group (incidence rate ratio (IRR): 1.1 in the 2,500–3,999 g group, IRR: 1.3 in the 37w0d–39w6d group). In particular, the risks of neonatal mortality and infant mortality were higher in infants born at a birth weight above 3,500 g. Infants born at a birth weight above 3,500 g may include recipients of twin-to-twin transfusion syndrome. The most common causes of infant mortality are accidental death and sudden infant death syndrome (SIDS). We considered the possibility that infants treated as healthy newborns and whose mothers were discharged from the hospital without adequate twin care guidance may be more likely to experience unintentional accidents and SIDS at home. The present study suggested that creating a new twin birth weight standard curve and guidance on managing twins at home for full-term and normal birth weight infants may lead to a reduction in infant deaths.

Dichorionic quadruplet pregnancy comprising monozygotic triplets and singleton after intracytoplasmic sperm injection and transfer of two fresh embryos: a case report

Monozygotic triplet pregnancies are very rare in assisted reproductive technology, and the relationship between monozygotic multiple pregnancies and several assisted reproductive techniques, including blastocyst transfer, remains unclear. Here, the case of a 28-year-old female patient with dichorionic quadruplet pregnancy following intracytoplasmic sperm injection and transfer of two day-3 fresh embryos, without assisted hatching, is reported. At 7 weeks following embryo transfer, the dichorionic quadruplet pregnancy, comprising monozygotic monochorionic triamniotic (MCTA) triplets plus a singleton, was detected by a transabdominal ultrasound scan. After counselling, the patient underwent selective reduction of the MCTA triplet pregnancy at 7 weeks after embryo transfer. The remaining singleton pregnancy was uneventful, resulting in a live birth at 38⁺ weeks. As the predictors of monozygotic multiple gestations remain poorly characterized, clinicians and patients should give great consideration to the risks associated with monozygotic multiple pregnancies, even if the patient has not undergone blastocyst transfer.

Retrospective comparison of pregnancy outcomes of fresh and frozen-warmed single blastocyst transfer: a 5-year single-center experience

PURPOSE

To assess whether live birth rates (LBR) and maternal/neonatal complications differed following single fresh and frozen-warmed blastocyst transfer.

METHODS

The present retrospective observational study analyzed 4,613 single embryo transfers (SET) (646 fresh and 3,967 frozen) from January 1, 2014, to December 31, 2018. Fresh embryo transfer at blastocyst stage was considered according to the age of the patient and her prognosis. In case of the risk of ovarian hyperstimulation syndrome, premature progesterone rise, non-optimal endometrial growth, or supernumerary embryos, cryopreservation with subsequent frozen embryo transfer (FET) was indicated.

RESULTS

No differences in LBR were recorded. Fresh embryo transfers yielded an increase both in neonatal complications OR 2.15 (95% CI 1.20-3.86, p 0.010), with a higher prevalence of singletons weighting below the 5th percentile (p 0.013) and of intrauterine growth retardation (p 0.015), as well as maternal complications, with a higher placenta previa occurrence OR 3.58 (95% CI 1.54-8.28, p 0.003), compared to FET.

CONCLUSION

LBR appears not to be affected by the transfer procedure preferred. Fresh embryo transfer is associated with higher risk of neonatal complications (specifically a higher prevalence of singletons weighting below the 5th percentile and of intrauterine growth retardation) and placenta previa. Reflecting on the increased practice of ART procedures, it is imperative to understand whether a transfer procedure yields less complications than the other and if it is time to switch to a "freeze-all" procedure as standard practice.

TRIAL REGISTRATION

Clinical Trial Registration Number: NCT04310761. Date of registration: March 17, 2020, retrospectively registered.

Protective placental inflammatory and oxidative stress responses are attenuated in the context of twin pregnancy and chorioamnionitis in assisted reproduction

PURPOSE

Assisted reproduction technologies (ART) are associated with increased risks of pregnancy complications and obstetric interventions. Here, we aimed to determine if ART affects placental inflammation and oxidative stress as a mechanism for unfavorable pregnancy outcomes.

METHODS

The levels of six cytokines (IFN-γ, IL-1β, IL-6, IL-8, IL-10, TNFα) were measured using multiplex ELISA. The activity of four antioxidant enzymes (glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase, superoxide dismutase) and levels of two antioxidants (GSH, vitamin E) were measured using commercial/in-house assays. Markers were compared between ART and unassisted pregnancies, and then groups were stratified using ICD9/10 codes to determine differences in specific clinical contexts.

RESULTS

In unassisted twin pregnancies, there was a trend of decreased cytokine levels (IL-1β, IL-6, IL-8, TNFα, p < 0.05), but cytokines in ART twins were the same or higher. Additionally, GST and GPx activities were lower in unassisted twins, and vitamin E levels were higher in ART twins (p < 0.05). In pregnancies complicated by chorioamnionitis, there was a trend of increased cytokine levels in unassisted pregnancies (IL-1β, IL-6, and IL-8, p < 0.05). No increase was observed in ART, and IFN-γ and TNFα were decreased (p < 0.05). Placental GST and GPx activities were higher in unassisted pregnancies with chorioamnionitis compared to ART (p < 0.05).

CONCLUSION

Attenuation of protective placental inflammatory and oxidative stress responses may play a role in the underlying pathogenesis of negative birth outcomes in ART, expanding our understanding of adverse pregnancy outcomes when ART is used to conceive.

Evaluation of clinical parameters as predictors of monozygotic twins after single frozen embryo transfer

Objective

To determine if recent evolutions in laboratory protocols, including the increased use of natural cycles and the use of a hyaluronan-containing transfer medium, affected the rate of monozygotic twin (MZT) pregnancies after single frozen embryo transfer (FET).

Design

Retrospective cohort study.

Setting

Urban university-based fertility center.

Patients

Patients who underwent single FET between January 2016 and December 2018 resulting in an intrauterine pregnancy.

Interventions

Transition to a transfer protocol with a hyaluronan-containing transfer medium in July 2017.

Main Outcome Measures

Number of MZT pregnancies.

Results

There were 1,619 cycles that met the inclusion criteria and 31 (1.9%) resulted in MZT pregnancies. A hyaluronan-containing transfer medium was used in 875 (54.1%) cycles. Programmed cycles were used for 1,385 (85.5%) FETs and 234 (14.5%) cycles were natural. The mean age at FET, oocyte age, endometrial echo thickness, inner cell mass grade, trophectoderm grade, expansion, and day of blastocyst vitrification were similar between the groups. The use of a hyaluronan-containing transfer medium resulted in fewer MZTs. After controlling potential confounders with a multivariate regression, the use of the hyaluronan-containing medium still resulted in fewer MZTs. Monozygotic twins were colinear with preimplantation genetic testing (PGT), so PGT was excluded as a variable in our regression. A regression of PGT only cycles showed that the use of the hyaluronan-containing medium was still associated with a reduction in MZT pregnancies.

Conclusions

The use of a hyaluronan-containing transfer medium was associated with a lower rate of MZTs. Other clinical parameters, including cycle type, were not associated with changes in the number of MZTs. The use of PGT needs to be further investigated as a risk factor for MZTs.

Blastocyst morphology is associated with the incidence of monozygotic twinning in assisted reproductive technology

BACKGROUND

An increased incidence of monozygotic twinning after a blastocyst transfer has been previously reported in assisted reproductive technology treatment. It is uncertain whether this phenomenon is due to the extended culture time, culture medium, or inherent blastocyst parameters.

OBJECTIVE

This study aimed to investigate the association between blastocyst parameters (in vitro culture time, blastocyst stage, and inner cell mass and trophectoderm grading) and the incidence of monozygotic twinning after assisted reproductive technology.

STUDY DESIGN

This was a retrospective cohort study employing data from a multicenter, large, electronic database from 4 academic hospitals. All clinical pregnancies after a single blastocyst transfer between January 2014 and February 2020 were included. Blastocyst morphology was evaluated based on the Gardner grading system, considering the blastocyst stage, and inner cell mass and trophectoderm grading (grades A, B, and C). Monozygotic twinning was defined as ≥2 fetal heartbeats in a single gestational sac or 2 gestational sacs with sex concordance at birth. The multivariable predicted marginal proportions from logistic regression models were used to compute adjusted relative risks for the association between blastocyst parameters and the incidence of monozygotic twinning.

RESULTS

The overall monozygotic twinning rate was 1.53% (402 of 26,254 cases). The monozygotic twinning was not associated with the culture time in vitro (day 5 vs day 6) or blastocyst stage (early, blastocyst, expanded, hatching, and hatched). Alternatively, monozygotic twinning was associated with lower inner cell mass grading (B vs A: adjusted relative risk, 1.67 [95 % confidence interval, 1.28-2.25]; C vs A: adjusted relative risk, 1.98 [95% confidence interval, 1.18-3.11]) and higher trophectoderm grading (B vs C: adjusted relative risk, 1.38 [95% confidence interval, 1.03-1.92]; A vs C: adjusted relative risk, 2.14 [95% confidence interval, 1.45-3.20]). The incidence of monozygotic twinning was the lowest in blastocysts with grade A inner cell mass and grade B or C trophectoderm (0.82%, as the reference) and the highest in blastocysts with grade B or C inner cell mass and grade A trophectoderm (2.40%; adjusted relative risk, 2.62; 95% confidence interval, 1.60-4.43). The incidence of monozygotic twinning in blastocysts with consistent inner cell mass or trophectoderm grading was somewhere in between (both A: 1.58%; adjusted relative risk, 1.86 [95% confidence interval, 1.23-3.04]; both B or C: 1.59%; adjusted relative risk, 1.84 [95% confidence interval, 1.29-2.90]).

CONCLUSION

Higher risk of monozygotic twinning was associated with blastocyst morphology specific to those blastocysts with loosely arranged inner cell mass cells combined with tightly packed trophectoderm cells.

On the origin of zygosity and chorionicity in twinning: evidence from human in vitro fertilization

Assisted reproduction is presumed to increase monozygotic twin rates, with the possible contribution of laboratory and medical interventions. Monozygotic dichorionic gestations are supposed to originate from the splitting of an embryo during the first four days of development, before blastocyst formation. Single embryo transfers could result in dichorionic pregnancies, currently explained by embryo splitting as described in the worldwide used medical textbooks, or concomitant conception. However, such splitting has never been observed in human in vitro fertilization, and downregulated frozen cycles could also produce multiple gestations. Several models of the possible origins of dichorionicity have been suggested. However, some possible underlying mechanisms observed from assisted reproduction seem to have been overlooked. In this review, we aimed to document the current knowledge, criticize the accepted dogma, and propose new insights into the origin of zygosity and chorionicity.

Uterine Transplantation: Review of Livebirths and Reproductive Implications

Uterine transplantation (UTx) is a fertility restoring treatment for women with absolute uterine factor infertility. At a time when there is no question of the procedure's feasibility, and as the number of livebirths begins to increase exponentially, various important reproductive, fetal, and maternal medicine implications have emerged. Detailed outcomes from 17 livebirths following UTx are now available, which are reviewed herein, along with contextualized extrapolation from pregnancy outcomes in other solid organ transplants. Differences in recipient demographics and reproductive aspirations between UTx and other transplant recipients make extrapolating management strategies and outcomes in other solid organ transplants inappropriate. Whereas preterm delivery remains prominent, small for gestational age or hypertensive disorders do not appear to be as prevalent following UTx when compared to other solid organ transplants. Given the primary objective of undertaking UTx is to achieve a livebirth, publication of reproductive outcomes is essential at this early stage, to reflect on and optimize the management of future cases.

Clinical and perinatal outcomes of fresh single-blastocyst-transfer cycles under an early follicular phase prolonged protocol according to day of trigger estradiol levels

Backgroud

This study’s objectives were to compare the clinical, perinatal, and obstetrical outcomes of patients with different estradiol (E₂) levels in fresh single-blastocyst-transfer (SBT) cycles under an early follicular phase prolonged regimen on the day of trigger.

Methods

We recruited patients in fresh SBT cycles (n = 771) undergoing early follicular phase prolonged protocols with β-hCG values above 10 IU/L between June 2016 and December 2018. Patients who met the inclusion and exclusion criteria were divided into four groups according to their serum E₂ level percentages on the day of trigger: <25^th, 25^th–50^th, 51^st–75^th, and >75^th percentile groups.

Results

Although the rates of clinical pregnancy (85.57% (166/194)), embryo implantation 86.60% (168/194), ongoing pregnancy (71.13% (138/194)), and live birth (71.13% (138/194)) were lowest in the >75th percentile group, we did not observe any significant differences (all P > 0.05). We used this information to predict the rate of severe ovarian hyperstimulation syndrome (OHSS) area under the curve (AUC) = 72.39%, P = 0.029, cut off value of E₂ = 2,893 pg/ml with the 75% sensitivity and 70% specificity. The 51^st–75^th percentile group had the highest rates of low birth weight infants (11.73% (19/162), P = 0.0408), premature delivery (11.43% (20/175), P = 0.0269), admission to the neonatal intensive care unit (NICU) (10.49% (17/162), P = 0.0029), twin pregnancies (8.57% (15/175), P = 0.0047), and monochorionic diamniotic pregnancies (8.57% (15/175); P = 0.001). We did not observe statistical differences in obstetrics complications, including gestational diabetes mellitus (GDM), gestational hypertension, placenta previa, premature rupture of membranes (PROM), and preterm premature rupture of membranes (PPROM).

Conclusion

We concluded that serum E₂ levels on the day of trigger were not good predictors of live birth rate or perinatal and obstetrical outcomes. However, we found that high E₂ levels may not be conducive to persistent pregnancies. The E₂ level on the day of trigger can still be used to predict the incidence of early onset severe OHSS in the fresh SBT cycle.

A rare case of heterotopic pregnancy after a single embryo transfer: A case report and literature review

Heterotopic pregnancy (HP) is a rare but life-threatening disease. We report a rare case of HP that occurred after single embryo transfer (SET) with spontaneous natural pregnancy possibly due to sexual intercourse (SI) during assisted reproductive technology treatment and reviewed previous reports. A 39-year-old woman at 7 weeks 5 days' gestation with anti-sperm antibody who underwent a single frozen-thawed embryo transfer in her natural cycle presented with lower abdominal pain and vaginal bleeding. She had several SIs before the day of SET. A viable intrauterine fetus and an extrauterine mass at the right adnexa were detected on transvaginal ultrasonography. An emergent laparoscopic surgery showed a swollen right fallopian tube, and right salpingectomy was performed. Unfortunately, intrauterine fetal death was diagnosed at 19 weeks' gestation. In conclusion, the possibility of HP should be considered in patients with SIs around the day of SET.

Obstetric and perinatal risks in 4601 singletons and 884 twins conceived after fresh blastocyst transfers: a Nordic study from the CoNARTaS group

STUDY QUESTION

Are obstetric and perinatal outcomes in pregnancies after fresh blastocyst transfer (BT) comparable with those born after fresh cleavage stage transfer (CT) and spontaneous conception (SC)?

SUMMARY ANSWER

Fresh BT is associated with a higher risk of placental and perinatal complications.

WHAT IS KNOWN ALREADY

BT optimizes the selection of top-quality embryos and increases pregnancy and live birth rates per transfer compared to CT. However, concerns have been raised as extended culture duration may increase obstetric complications and impair perinatal outcomes. Previous studies have shown a higher risk of preterm birth (PTB) among infants born after BT compared with CT. Pregnancies after BT are also prone to a higher risk of same-sex twins after single embryo transfer (SET).

STUDY DESIGN, SIZE, DURATION

A retrospective register-based cohort study used data from Denmark, Norway and Sweden including three cohorts: 56 557 singletons and 16 315 twins born after fresh IVF/ICSI cycles and 2 808 323 SC singletons in Denmark (birth years 1997-2014), Norway (2010-2015) and Sweden (2002-2015). Of the fresh IVF/ICSI singletons, 4601 were born after BT and 51 956 after CT. The twin cohort consisted of 884 fresh IVF/ICSI children born after BT and 15 431 fresh IVF/ICSI children born after CT.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data were obtained from a large Nordic cohort of children born after ART and SC initiated by the Committee of Nordic ART and Safety (CoNARTaS). The CoNARTaS cohort was established by cross-linking National ART-, Medical Birth-, and National Patients Registers using the unique personal identification number, allocated to every citizen in the Nordic countries. Obstetric and perinatal outcomes after BT, CT and SC were compared using logistic regression analysis. For perinatal outcomes, we calculated gestational age based on the date of oocyte pick-up (OPU) and in sensitivity analyses on data from Denmark and Norway, we also calculated gestational age based on the second-trimester ultrasonography (US) scan. Risk of pregnancies with same-sex twins after SET was used as a proxy for risk of monozygotic twins. Adjustments were made for child's sex, birth year, parity (0 or >1), maternal age, body mass index, smoking, educational level, fertilization method (IVF/ICSI), the number of aspirated oocytes, SET and country. Information on educational level and the number of aspirated oocytes was not available for Norway. Children born after frozen embryo transfer were not included. The birth cohorts were restricted according to the year in which BT was introduced in the different countries.

MAIN RESULTS AND THE ROLE OF CHANCE

A higher risk of placenta previa was found in singleton pregnancies after BT compared with CT (adjusted odds ratio [aOR] 2.11 [95% CI 1.76; 2.52]). Singletons born after BT had a higher risk of PTB (aOR 1.14 [95% CI 1.01; 1.29]) compared with CT singletons, when estimated based on OPU. Furthermore, an altered male/female ratio (aOR 1.13 [95% CI 1.06; 1.21]) with more males following BT compared with CT was seen. Risk of same-sex twins after SET was higher after single BT compared with single CT (aOR 1.94 [95% CI 1.42; 2.60]).

LIMITATIONS, REASONS FOR CAUTION

Residual confounding cannot be excluded, in particular related to duration and cause of infertility that we could not adjust for due to lack of reliable data.

WIDER IMPLICATIONS OF THE FINDINGS

Extended embryo culture to the blastocyst stage has the potential to compromise obstetric and perinatal outcomes in fresh cycles. These results are important since an increasing number of IVF/ICSI treatments are performed as BT.

STUDY FUNDING/COMPETING INTEREST(S)

NORDFORSK (project no: 71450). The Research Fund of Rigshospitalet, Copenhagen University Hospital. ReproUnion Collaborative study, co-financed by the European Union, Interreg V ÖKS. Grants from Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement (LUA/ALF 70940), Hjalmar Svensson Research Foundation. The Research Council of Norway through its Centres of Excellence funding scheme, project number 262700. None of the authors has any conflicts of interests to declare regarding this study.

TRIAL REGISTRATION NUMBER

ISRCTN11780826.

High grade trophectoderm is associated with monozygotic twinning in frozen-thawed single blastocyst transfer

BACKGROUND

The aim of this study was to explore specific factors that predispose to monozygotic twinning (MZT) at the blastocyst stage.

METHODS

This was a retrospective observational study of a cohort of 2863 pregnancies after single blastocyst transfer (SBT) between January 2011 and June 2019 in our hospital. MZT pregnancy was identified as the number of fetuses exceeded the number of gestational sacs (GSs) by transvaginal ultrasound at 6-7 gestational weeks. The incidences of MZT regarding the maternal age at oocyte retrieval, paternal age, ovarian stimulation protocol, fertilization method, endometrium preparation protocol, vitrified day, and the Gardner grading of the blastocyst were calculated. The serum estrogen (E₂), progesterone (P) levels, endometrium thickness and serum hCG levels on day 11 after embryo transfer (ET) were compared between the MZT and singleton pregnancies. Statistical analyses were used appropriately.

RESULTS

Fifty-one MZT pregnancies (1.78%) were identified. The only significant differences observed between MZT and singleton pregnancies were the proportion of TE grade (P = 0.022) and the hCG levels on day 11 after ET (P = 0.003). Multivariate logistic regression revealed that trophectoderm (TE) grade was an independent factor affecting MZT, the adjusted odds ratios (aORs) of grade A and B TE were 5.46 [95% confidential interval (CI) 1.48-20.16, P = 0.011) and 3.96 (95% CI 1.17-13.40, P = 0.027) compared to grade C respectively. There were no significant associations between the parental age, fertilization method, ovarian stimulation protocol, endometrium preparation protocol, vitrified day, expansion stage, inner cell mass (ICM) grade and MZT.

CONCLUSIONS

TE grade is associated with MZT at the blastocyst stage, potentially mediated via increased secretion of hCG from more well developed TE. Increased hCG secretion in turn may prolong the implantation window to support the embryo splitting.

Monozygotic twinning following embryo biopsy at the blastocyst stage

Objective:

Monozygotic twinning incidence following preimplantation genetic testing in embryos at cleavage-stage does not appear to increase; however, data regarding the possible impact of the blastocyst-stage preimplantation genetic testing is lacking. We compared the incidence of monozygotic twinning in preimplantation genetic testing cycles performed at the blastocyst-stage, versus cycles without PGT, following single embryo transfer.

Methods:

In this retrospective cohort study, we analyzed the incidence of twin pregnancies in patients undergoing intracytoplasmic sperm injection and blastocyst-preimplantation genetic testing (253 cycles), versus a period-matched control population of patients undergoing intracytoplasmic sperm injection and single embryo transfer without preimplantation genetic testing (606 cycles).

Results:

The overall monozygotic twinning rate was 14/859 (1.6%) per clinical pregnancy. The incidence of zygotic splitting following intracytoplasmic sperm injection and preimplantation genetic testing was 3.5% (95% Confidence interval 1.8%-6.6%) versus 0.8% (95% Confidence interval 0.3%-1.9%) following intracytoplasmic sperm injection without preimplantation sperm injection. After adjusting for potential confounders, preimplantation genetic testing cycles were associated with an increase in the incidence of monozygotic twinning when compared to cycles without embryo biopsy (Odd ratio 3.44, 95% Confidence interval 1.05-11.27, p=0.041).

Conclusions:

Our findings indicate that embryo biopsy for preimplantation genetic testing performed at the blastocyst stage is associated to an increase in the incidence of monozygotic twinning. Further validation in larger sample size studies is warranted. Patients undergoing preimplantation genetic testing must receive proper counselling about the potential risks of the technique.

Monozygotic dichorionic-diamniotic twin pregnancy after single embryo transfer at blastocyst stage: a case report

Single embryo transfer is highly encouraged on in vitro fertilization due to its lower rates of multiple pregnancy. Nevertheless, the likelihood of multiple pregnancy is higher when using assisted reproductive technology, probably because of embryo handling. Timing is crucial in the post-fertilization division of a single embryo to establish the amniocity and chorionicity of the gestation. In the case reported a 38 year-old woman, nulligravid, had a single blastocyst implanted, which resulted in monozygotic dichorionic-diamniotic twins. Despite being rare, there are reports of similar cases questioning the current knowledge on time of embryo division and the impact of assisted reproduction.

Comparing the cumulative live birth rate of cleavage-stage versus blastocyst-stage embryo transfers between IVF cycles: a study protocol for a multicentre randomised controlled superiority trial (the ToF trial)

INTRODUCTION

In vitro fertilisation (IVF) has evolved as an intervention of choice to help couples with infertility to conceive. In the last decade, a strategy change in the day of embryo transfer has been developed. Many IVF centres choose nowadays to transfer at later stages of embryo development, for example, transferring embryos at blastocyst stage instead of cleavage stage. However, it still is not known which embryo transfer policy in IVF is more efficient in terms of cumulative live birth rate (cLBR), following a fresh and the subsequent frozen-thawed transfers after one oocyte retrieval. Furthermore, studies reporting on obstetric and neonatal outcomes from both transfer policies are limited.

METHODS AND ANALYSIS

We have set up a multicentre randomised superiority trial in the Netherlands, named the Three or Fivetrial. We plan to include 1200 women with an indication for IVF with at least four embryos available on day 2 after the oocyte retrieval. Women are randomly allocated to either (1) control group: embryo transfer on day 3 and cryopreservation of supernumerary good-quality embryos on day 3 or 4, or (2) intervention group: embryo transfer on day 5 and cryopreservation of supernumerary good-quality embryos on day 5 or 6. The primary outcome is the cLBR per oocyte retrieval. Secondary outcomes include LBR following fresh transfer, multiple pregnancy rate and time until pregnancy leading a live birth. We will also assess the obstetric and neonatal outcomes, costs and patients' treatment burden.

ETHICS AND DISSEMINATION

The study protocol has been approved by the Central Committee on Research involving Human Subjects in the Netherlands in June 2018 (CCMO NL 64060.000.18). The results of this trial will be submitted for publication in international peer-reviewed and in open access journals.

TRIAL REGISTRATION NUMBER

Netherlands Trial Register (NL 6857).

Monozygotic dichorionic-diamniotic pregnancies following single frozen-thawed blastocyst transfer: a retrospective case series

BACKGROUND

The primary aim of the study is to report cases of monozygotic dichorionic-diamniotic (DC-DA) pregnancies after single frozen-thawed blastocyst transfer.

METHODS

This is a retrospective case series. All single frozen-thawed blastocyst transfer cycles performed between June 2013 and December 2018 at the Shanghai Ji Ai Genetics and IVF Institute, Obstetrics and Gynecology Hospital, Fudan University, Shanghai, China, were reviewed retrospectively. We included frozen embryo transfer (FET) cycles which clinical pregnancy was confirmed with multiple gestational sacs showed on ultrasonography at around 6 to 7 weeks of gestation. We then conducted an in-depth analysis to further exclude cases which contained newborns of different genders or natural FET cycles.

RESULTS

Five thousand four hundred fifteen frozen-thawed single blastocyst transfer cycles were preformed between June 2013 and December 2018 at the Shanghai Ji Ai Genetics and IVF Institute, Obstetrics and Gynecology Hospital, Fudan University, Shanghai, China. Of these, fourteen women underwent a single blastocyst transfer and then achieved clinical pregnancy with an ultrasound diagnosis of multi-chorionic pregnancy. With one natural cycle FET excluded, we finally included thirteen single blastocyst transfer cycles performed in down-regulated controlled FET or hormone replacement FET, in which the possibility of concurrently spontaneous pregnancy was extremely small. These included 13 cases reveal the phenomenon of monozygotic DC-DA twinning after single blastocyst transfer, which challenges the classical theory that only monochorionic pregnancy could happen after 3 days of fertilization.

CONCLUSION

This case series suggest that single blastocyst transfer could result DC-DA pregnancies during IVF treatment.

Incidences and risk factors of moderate-to-severe ovarian hyperstimulation syndrome and severe hemoperitoneum in 1,435,108 oocyte retrievals

RESEARCH QUESTION

What are the risk factors affecting the incidences of moderate-to-severe ovarian hyperstimulation syndrome (OHSS) and severe hemoperitoneum in assisted reproductive technology (ART) treatment cycles?

DESIGN

A retrospective cohort study was conducted on 1,435,108 oocyte retrieval cycles among Japanese ART registry data between 2007 and 2015. The study included 11,378 cycles with moderate-to-severe OHSS, 1182 cycles with severe hemoperitoneum, including 27 cycles with both conditions, and 1,422,575 cycles without moderate-to-severe OHSS and severe hemoperitoneum.

RESULTS

The incidences of moderate-to-severe OHSS and severe hemoperitoneum were 0.79% and 0.08%, respectively, and decreased by 0.57-fold and 0.29-fold from 2007 to 2015, respectively. In cycles with OHSS and cycles with hemoperitoneum women were younger (odds ratios [OR] 0.91 and 0.95, respectively) and had more retrieved oocytes (OR 1.09 and 1.01, respectively) compared with cycles without both complications. The use of a gonadotrophin-releasing hormone (GnRH) agonist protocol for ovarian stimulation was the highest risk factor in cycles with OHSS and hemoperitoneum (OR 1.83 and 1.24, respectively), followed by GnRH antagonist protocol (reference), gonadotrophin with or without oral medicine (OR 0.45 and 0.56, respectively) and natural or oral medicine (OR 0.02 and 0.19, respectively). In fresh embryo transfer, clinical pregnancy was associated with an increased risk of OHSS and hemoperitoneum (OR 1.19 and 2.34, respectively).

CONCLUSIONS

The highest risk factors affecting OHSS and hemoperitoneum were the use of a GnRH agonist protocol and clinical pregnancy following fresh embryo transfer. The incidences of OHSS and hemoperitoneum have decreased yearly with a reduction of GnRH agonist use and fresh embryo transfer.

Double trouble? Clinic-specific risk factors for monozygotic twinning

OBJECTIVE

To investigate clinic-specific risk factors for monozygotic twinning (MZT) using a large, electronic database.

DESIGN

Retrospective case-control study.

SETTING

Infertility clinics.

PATIENT(S)

Using an electronic medical record system, viable clinical pregnancy (confirmation of a gestational sac(s) and presence of at least one fetal pole with a heartbeat on first trimester ultrasound), data were obtained from homologous in vitro fertilization (IVF) cycles after single ET from June 1, 2004, to December 31, 2016. Monozygotic twinning was defined as a pregnancy with two fetal heartbeats on ultrasound with sex concordance at birth.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Risk factors for MZT including cycle type, method of insemination, and method of cryopreservation.

RESULT(S)

Of the 28,265 IVF cycles that met inclusion criteria over the study period, 8,749 (31.0%) resulted in a viable intrauterine clinical pregnancy. There were 102 (2.7%) MZT in the fresh cycle cohort and 133 (2.7%) in the frozen cycle cohort. Neither cryopreservation nor the method of cryopreservation was a significant risk factor for MZT. However, the use of sequential media was an independent risk factor for MZT in fresh, but not frozen, ETs (odds ratio = 1.72, 95% confidence interval, 1.10-2.68). Significant differences were seen in the incidence of MZT between clinics, and this difference persisted after controlling for known risk factors (clinic 0, reference; clinic 2, odds ratio = 2.22; 95% confidence interval, 1.48-3.32; clinic 3, odds ratio = 1.93; 95% confidence interval, 1.30-2.87).

CONCLUSION(S)

Differences in MZT rates exist between individual IVF clinics, suggesting that variations in practice patterns may contribute to this event. The present study noted the use of sequential media was an independent risk factor for fresh but not frozen cycles.

Preimplantation Genetic Testing: Where We Are Today

BACKGROUND

Preimplantation genetic testing (PGT) is widely used today in in-vitro fertilization (IVF) centers over the world for selecting euploid embryos for transfer and to improve clinical outcomes in terms of embryo implantation, clinical pregnancy, and live birth rates.

METHODS

We report the current knowledge concerning these procedures and the results from different clinical indications in which PGT is commonly applied.

RESULTS

This paper illustrates different molecular techniques used for this purpose and the clinical significance of the different oocyte and embryo stage (polar bodies, cleavage embryo, and blastocyst) at which it is possible to perform sampling biopsies for PGT. Finally, genetic origin and clinical significance of embryo mosaicism are illustrated.

CONCLUSIONS

The preimplantation genetic testing is a valid technique to evaluated embryo euploidy and mosaicism before transfer.

Monochorionic diamniotic twins: What do I tell the prospective parents?

Monochorionic diamniotic twins occur in about 1 in 300 pregnancies. Compared with dichorionic twins, they face increased risks because of the shared circulation. In about 15%, an imbalance in blood exchange occurs, such as twin-twin transfusion syndrome and twin anemia polycythemia sequence. In this review, we summarize the latest evidence on the management of monochorionic diamniotic twin pregnancies and their specific complications, with a focus on information that is relevant for prospective parents.

Successful monozygotic triplet pregnancy after a single blastocyst transfer following in vitro maturation of oocytes from a woman with polycystic ovary syndrome: a case report

Background

Although women with polycystic ovarian syndrome (PCOS)-related sub-fertility are high responders to controlled ovarian stimulation, it is difficult to obtain mature oocytes in these women. Therefore, in vitro maturation (IVM), which is the technique of letting the contents of the ovarian follicles and the oocytes inside mature in vitro, has often been proposed in such women. We describe the first successful delivery of monozygotic triplets resulting from transfer of a single blastocyst following IVM of oocytes.

Case presentation

A 32-year-old nulligravida female with PCOS underwent IVM. She underwent vitrified-warmed single blastocyst transfer following IVM, and a dichorionic triamniotic triplet pregnancy was confirmed at 8 weeks. Healthy triplets were delivered by cesarean section at 33 weeks’ gestation. This is the first case of monozygotic triplets derived from IVM oocytes that were successfully delivered. The determination of chorionicity and amnionicity is generally supposed until 3 days after fertilization, and no division or splitting of her embryo was observed on transfer. Interestingly, her embryo might have split after the transfer, resulting in a dichorionic triamniotic triplet pregnancy.

Conclusions

Patients should be informed of a possible increased risk of monozygotic multiple pregnancies after single embryo transfer following IVM.

Zygotic splitting following embryo biopsy: a cohort study of 207 697 single-embryo transfers following IVF treatment

OBJECTIVE

To evaluate the risk of monozygotic splitting with embryo biopsy during in vitro fertilisation (IVF).

DESIGN

A cohort study.

SETTING

Anonymised assisted reproductive technology national data from the Human Fertilisation and Embryology Authority, UK.

POPULATION

Women undergoing single-embryo transfer (SET) following either pre-implantation genetic testing (PGT) involving embryo biopsy or IVF without PGT.

METHODS

Data on women undergoing SET either following PGT and non-PGT IVF treatment in 2000-2016 were analysed to compare the risk of zygotic splitting and monozygotic twining. Logistic regression analysis was performed adjusting for potential confounders.

MAIN OUTCOMES

Monozygotic spitting, monozygotic twin birth.

RESULTS

Data comprising a total of 207 697 SET cycles (4544 following PGT and 203 153 following non-PGT IVF) were analysed. The live birth rate per embryo transfer was 31.9% (95% confidence interval [CI] 30.5-33.2%) following PGT and 26.9% (95% CI 26.7-27.1%) following non-PGT IVF. The incidence of zygotic splitting following PGT was 2.4% (95% CI 1.7-3.3%) versus 1.5% (95% CI 1.4-1.6%) following non-PGT IVF. There was a significantly higher risk of zygotic splitting with PGT versus non-PGT IVF cycles (odds ratio [OR] 1.64, 95% CI 1.19-2.27). The higher risk of zygotic splitting with PGT cycles remained significant after adjusting for potential confounders (adjusted OR 1.51, 95% CI 1.06-2.15).

CONCLUSIONS

The present study demonstrated an increased risk of monozygotic splitting with embryo biopsy. Given the current sparse literature, it is important to accumulate further evidence to validate the findings.

TWEETABLE ABSTRACT

A likely increased risk of monozygotic splitting following embryo biopsy.

Assisted reproductive technology strategies in uterus transplantation

The development of assisted reproductive technology (ART) through four decades has led to offer the ultimate treatment for nearly all forms of infertility. The only remaining factor of childlessness however that still eludes ART and its routine variants are the absolute uterine infertility factors, for which the only option is an experimental approach, uterus transplantation. Progresses has been made over the past few years, and more are underway for simplifying the process notably for simplifying the uterus extraction step performed in the uterus donor. Furthermore, as the technique is being better mastered, the original indications for uterus transplantation, the congenital or acquired absence of the uterus, are now widened to also include incurable uterine fibrosis, or Asherman's syndrome. The ART-related practicalities of uterus transplantation, ovarian stimulation and uterine priming are being discussed in the present review.

Analysis of 122 triplet and one quadruplet pregnancies after single embryo transfer in Japan

RESEARCH QUESTION

What is the prevalence of triplet and quadruplet pregnancies after single embryo transfer (SET) in Japan.

DESIGN

A retrospective observational study was conducted on 274,605 pregnancies after 937,848 SET cycles in registered assisted reproductive technology (ART) data from the Japanese ART national registry database between 2007 and 2014. A questionnaire survey of ART centres was also conducted. Data on pregnancies with embryo division into three or more after SET were analysed.

RESULTS

According to the Japanese ART national registry database, SET resulted in 109 triplet pregnancies (0.04% of pregnancies), and the questionnaire reports from 31 centres revealed 33 triplet and one quadruplet pregnancies. After exclusion of 20 duplicated cases, 122 triplet and one quadruplet pregnancies included 46 monochorionic (one gestational sac [37.4%]), 18 dichorionic (two gestational sacs [14.6%]) and 59 trichorionic pregnancies (three gestational sacs [48.0%]). Compared with singleton pregnancies, patients with monozygotic triplet or quadruplet pregnancies were less frequently diagnosed with unexplained infertility (P = 0.004), more often received gonadotrophin injections for ovarian stimulation in 39 cases with information available (P = 0.021) and underwent more blastocyst transfers and assisted hatching (P = 0.002 and P < 0.001, respectively). The proportion of live birth, defined as at least one baby born, excluding induced abortion, was 64.6% (73/116 pregnancies) of monozygotic triplet or quadruplet pregnancies.

CONCLUSIONS

Combined Japanese ART national registry and survey data revealed 122 triplet and one quadruplet pregnancies, the majority after cryopreserved embryo transfer. Most were conceived after blastocyst transfer and often after assisted hatching, which are potential risk factors for zygotic splitting.

Risk factors for monozygotic twinning after in vitro fertilization: a systematic review and meta-analysis

OBJECTIVES

To establish the risk factors for monozygotic twin (MZT) and monochorionic twin (MCT) pregnancies after in vitro fertilization (IVF).

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Women who achieved MZT and non-MZT pregnancies through IVF.

INTERVENTION(S)

Systematic search of Medline from January 1995 to October 2018 with cross-checking of references from relevant articles in English.

MAIN OUTCOME MEASURE(S)

Possible risk factors for MZT or MCT pregnancies after IVF, comprising extended embryo culture, insemination method (conventional IVF and intracytoplasmic sperm injection [ICSI]), embryo biopsy for preimplantation genetic testing for aneuploidies or for monogenic/single-gene defects (PGT-A or PGT-M) programs, assisted hatching (AH), oocytes donation, female age, and embryo cryopreservation.

RESULT(S)

A total of 40 studies were included. Blastocyst transfer compared with cleavage-stage embryo transfer, and female age <35 years were associated with a statistically significant increase in the MZT and MCT pregnancy rate after IVF: (23 studies, OR 2.16, 95% CI, 1.74-2.68, I²=78%; 4 studies, OR 1.29; 95% CI, 1.03-1.62, I²=62%; and 3 studies, OR 1.90, 95% CI, 1.21-2.98, I²=59%; 2 studies, OR 2.34; 95% CI, 1.69-3.23, I²=0, respectively). Conventional IVF compared with ICSI and assisted hatching were associated with a statistically significantly increased risk of MZT pregnancy (9 studies, OR 1.19, 95% CI, 1.04-1.35, I²=0; 16 studies, OR 1.17, 95% CI, 1.09-1.27, I²=29%, respectively). Embryo biopsy for PGT-A or PGT-M, embryo cryopreservation, and oocytes donation were not associated with MZT pregnancies after IVF.

CONCLUSION(S)

Blastocyst transfer is associated with an increased risk of both MZT and MCT pregnancies after IVF. Further evidence is needed to clarify the impact of female age, insemination method and AH on the investigated outcomes.

Perinatal outcomes following assisted reproductive technology

As the use of routine assisted reproductive technology (ART) becomes widespread along with the extended applications such as ART with donor gametes, surrogacy, and preimplantation genetic testing (PGT), it becomes more pertinent to evaluate risks associated with them. Perinatal outcomes and long-term safety for the women and children are paramount. In this review, we aimed to detail the perinatal outcomes in relation to the ART procedures routinely applied as the extended applications of ART with a focus on singleton pregnancies. While there seems to be a higher risk of adverse perinatal outcomes with some of the ART procedures, the absolute risk increase is generally low. It is important for clinicians to have this knowledge to better counsel and care for their patients.