The effect of early fetal losses on singleton assisted-conception pregnancy outcomes

The vanishing twin: Diagnosis and implications

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

Risks of nonchromosomal birth defects, small-for-gestational age birthweight, and prematurity with in vitro fertilization: effect of number of embryos transferred and plurality at conception versus at birth

PURPOSE

Excess embryos transferred (ET) (> plurality at birth) and fetal heartbeats (FHB) at 6 weeks' gestation are associated with reductions in birthweight and gestation, but prior studies have been limited by small sample sizes and limited IVF data. This analysis evaluated associations between excess ET, excess FHB, and adverse perinatal outcomes, including the risk of nonchromosomal birth defects.

METHODS

Live births conceived via IVF from Massachusetts, New York, North Carolina, and Texas included 138,435 children born 2004-2013 (Texas), 2004-2016 (Massachusetts and North Carolina), and 2004-2017 (New York) were classified by ET and FHB. Major birth defects were reported by statewide registries within the first year of life. Logistic regression was used to estimate adjusted odds ratios (AORs) and 95% CIs of the risks of a major nonchromosomal birth defect, small-for-gestational age birthweight (SGA), low birthweight (LBW), and preterm birth (≤36 weeks), by excess ET, and excess ET + excess FHB, by plurality at birth (singletons and twins).

RESULTS

In singletons with [2 ET, FHB =1] and [≥3 ET, FHB=1], risks [AOR (95% CI)] were increased, respectively, for major nonchromosomal birth defects [1.13 (1.00-1.27) and 1.18 (1.00-1.38)], SGA [1.10 (1.03-1.17) and 1.15 (1.05-1.26)], LBW [1.09 (1.02-1.13) and 1.17 (1.07-1.27)], and preterm birth [1.06 (1.00-1.12) and 1.14 (1.06-1.23)]. With excess ET + excess FHB, risks of all adverse outcomes except major nonchromosomal birth defects increased further for both singletons and twins.

CONCLUSION

Excess embryos transferred are associated with increased risks for nonchromosomal birth defects, reduced birthweight, and prematurity in IVF-conceived births.

Perinatal outcomes in vanishing twin pregnancies following assisted reproductive technology (ART) - a systematic review and meta-analysis

Objectives To compare the fetal and maternal outcomes in surviving singletons of vanishing twin, with singletons or twins, in pregnancies following assisted reproductive technology (ART). Content We searched the PubMed, Embase, Web of Science and Cochrane databases from the time of conception of the database until Dec 2019 to identify relevant published studies. Perinatal outcomes were synthesized with random effects meta-analysis using RevMan 5.3. Summary and Outlook Fifteen studies were included. Dichorionic twin pregnancies conceived by ART wherein the vanishing twin phenomenon occurred had a risk of fetal malformation similar to that of ART singleton pregnancies (OR=1.25; 95% CI 0.87-1.79) and a higher risk of fetal malformation compared with ART twin pregnancies (OR=1.82; 95% CI 1.23-2.70). Moreover, the remaining fetus in ART vanishing twin pregnancy was at a significantly higher risk of preterm birth (<37 weeks) compared to fetuses in ART singleton pregnancies (OR=2.41; 95% CI 1.46-3.99) and a markedly lower risk of preterm birth (<37 weeks) compared to the fetuses in ART twin pregnancies (OR=0.19; 95% CI 0.16-0.22). Meanwhile, the risk of delivery of infants who were small for gestational age (SGA) was significantly higher in ART vanishing twin pregnancies compared to that in ART singleton pregnancies (OR=2.70; 95% CI 1.39-5.24) and similar to that in ART twin pregnancies (OR=0.67; 95% CI 0.27-1.65). The risks of preterm birth and of the infant being SGA is higher for the remaining fetus in an ART vanishing twin pregnancy compared to those for the fetuses in ART singleton pregnancies; the risk of fetal malformation is also higher in such cases compared with ART twin pregnancies.

Neonatal outcomes of singleton live births with vanishing twin syndrome following double embryos transfer in assisted reproductive technology: a retrospective cohort study

Background

Women with vanishing twin syndrome are associated with increased risks of adverse neonatal outcomes, such as preterm birth (PTB) and low birthweight (LBW), compared with those in singleton live births following single embryo transfer (SET) in assisted reproductive technology (ART).

Methods

Anonymized data on all cycles performed in China were obtained from the Reproductive Medicine Department at the Third Affiliated Hospital of Zhengzhou University, which had involved 127597 cycles following double embryos transfer (DET), including 54585 fresh embryos transfer (ET) cycles and 73012 frozen embryos transfer (FET) cycles. In addition, the obstetric outcomes, such as gestation age, PTB, small for gestation age (SGA), birthweight (BW), LBW, congenital malformation, pediatric admission and Neonatal Intensive Care Unit (NICU) admission in the fresh ET and FET cycles, were analyzed. Moreover, logistic regression analysis was performed to adjust the confounders, including age of women, body weight index (BMI), value of AMH, infertile years, current cycle, antral follicles, cause of infertility, number of oocytes retrieved, endometrial thickness at the date of transplantation, number of high-quality embryos, and embryo stage.

Results

In the fresh ET cycles, the BW and gestational age in study group were lower than those in control group, which were (2962.4 ± 563.1vs. 3104.9 ± 498. 5, p = 0.000) and (262.8 ± 8.4 vs. 268.9 ± 13.9, p = 0.000), respectively. Relative to control group, the study group was linked with increased risks of PTB (adjusted odds ratio (aOR) 2.45, 95% CI:1.98–3.03, adjusted p = 0.000), LBW (aOR2.11, 95% CI:1.67–2.65, adjusted p = 0.000), pediatric admission (aOR 2.55, 95% CI2.07–3.13, adjusted p = 0.000), and NICU admission (aOR 1.98, 95% CI1.32–2.96, adjusted p = 0.001), but there were no statistically significant differences in the risks of SGA (aOR 1.09, 95% CI0.82–1.45, adjusted p = 0.960) and congenital malformation (aOR 0.94, 95% CI0.53–1.68, adjusted p = 0.640) between the two groups. In the FET cycles, the gestational age and BW in study group were lower than those in control group, which were (263.0 ± 15.7vs. 273.0 ± 10.5, p = 0.000) and (3099 ± 662.1vs. 3352 ± 671.5), respectively. The study group was associated with increased risks of PTB (aOR2. 45, 95% CI: 2.23–3.43, adjusted p = 0.000), LBW (aOR 2.67, 95% CI: 2.13–3.34, adjusted p = 0.000), pediatric admission (aOR2.62, 95% CI2.14–3.21, adjusted p = 0.000), and NICU admission (aOR 2.22, 95% CI1.43, 3.46, adjusted p = 0.001) compared with those in control group, but differences in the risks of SGA (aOR 0.98, 95% CI0.71–1.36, adjusted p = 0.730) and congenital malformation (aOR 0.99, 95% CI 0.60,1.63, adjusted p = 0.940) between the two groups were not statistically significant.

Conclusions

Our study finds that singleton live births with VTS have higher risks of LBW, PTB, pediatric admission and NICU admission than those without VTS in both the fresh and frozen cycles, even after adjusting for confounders. However, no increased risks of SGA or congenital malformation are observed in singleton live births in both the fresh and frozen ART cycles following DET.

Advanced Paternal Age Affects Sperm Count and Anogenital Distance in Mouse Offspring

In Western society, couples increasingly delay parenthood until later in life. Overall, studies have focused on the reproductive performance of older parents or the impact of advanced maternal age on pregnancy outcomes, but few studies have examined how advanced paternal age (APA) affects offspring health. The aim of this study was to investigate the impact of increasing paternal age on offspring reproductive performance and long-term metabolic health in a mouse model. Here, the same adult B6D2F1/J male mice were mated at 4, 12, and 18 months of age with 6- to 10-week-old naturally cycling CF1 females to generate 3 offspring cohorts conceived at increasing paternal ages PA4, PA12, and PA18. The offspring resulting from mating the same fathers at different ages (n = 20 per age; 10 males and 10 females) were maintained up to 20 weeks of age and morphometric parameters, growth curve, and glucose tolerance were measured. We found that increasing paternal age was associated with a trend toward longer time to conception. Litter sizes were not significantly different. Reassuringly, metabolic parameters and growth curve were not different in the 3 cohorts of offspring. Most importantly, increased paternal age (PA4 vs PA18) was associated with a statistically significant decrease in sperm concentration, sperm motility, and anogenital distance in offspring. These changes raise concerns about the potential impact of APA on the reproductive fitness in males of the next generation.

Early spontaneous multiple fetal pregnancy reduction is associated with adverse perinatal outcomes in in vitro fertilization cycles

The primary objective of this study is to investigate whether early spontaneous multiple fetal pregnancy reduction, also known as vanishing twin syndrome, is associated with adverse perinatal outcomes in fresh in vitro fertilization cycles. This is a retrospective cohort study of women with live singleton births with and without an early vanishing twin after fresh in vitro fertilization. Characteristics compared included incidence of preterm birth, overall birth weight, overall low birth weight, overall very low birth weight, and term low birth weight. In all, 4049 patients with live singleton births were included-853 and 3196 with and without a vanishing twin, respectively. The vanishing twin group had a lower overall birth weight compared to those without (3279.5 ± 369.9 vs 3368.6 ± 567.5 g; p < 0.01). Early vanishing twin was also associated with an increased odds of overall low birth weight (odds ratio: 1.75; 95% confidence interval: 1.36-2.25; p < 0.01) and increased odds of term low birth weight (odds ratio: 3.44; 95% confidence interval: 2.14-5.53; p < 0.01). Our study suggests that early vanishing twin is associated with lower overall birth weight and higher odds of overall low birth weight and term low birth weight in live singleton births after fresh in vitro fertilization.

Vanishing twin syndrome among ART singletons and pregnancy outcomes

STUDY QUESTION

Among babies born by ART, do singleton survivors of a vanishing twin have lower birth weight than other singletons?

SUMMARY ANSWER

Vanishing twin syndrome (VTS) was associated with lower birth weight among ART singletons; a sibship analysis indicated that the association was not confounded by maternal characteristics that remain stable between deliveries.

WHAT IS KNOWN ALREADY

Previous studies indicate that ART singletons with VTS have increased risk of adverse pregnancy outcomes, compared with other ART singletons. The potential contribution of unmeasured maternal background characteristics has been unclear.

STUDY DESIGN, SIZE AND DURATION

This was a Norwegian population-based registry study, including 17 368 mothers with 20 410 ART singleton deliveries between January 1984 and December 2013.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study population included 17 291 ART singletons without VTS, 638 ART singletons with VTS and 2418 ART singletons with uncertain vanishing twin status. We estimated differences in birth weight and gestational age comparing ART singletons with VTS first to all ART singletons without VTS, and subsequently to their ART siblings without VTS, using random- and fixed-effects linear regression, respectively. The corresponding comparisons for the associations with preterm birth and small for gestational age (SGA) were conducted using random-and fixed-effects logistic regression. The sibling analysis of preterm birth included 587 discordant siblings, while the sibling analysis of SGA included 674 discordant siblings.

MAIN RESULTS AND THE ROLE OF CHANCE

ART singletons with VTS had lower birth weight when compared to all ART singletons without VTS, with an adjusted mean difference (95% CI) of -116 g (-165, -67). When we compared ART singletons with VTS to their ART singletons sibling without VTS, the adjusted mean difference was -112 g (-209, -15). ART singletons with VTS also had increased risk of being born SGA, with an adjusted odds ratio (OR) (95% CI) of 1.48 (1.07, 2.03) compared to all ART singletons without VTS, and 2.79 (1.12, 6.91) in the sibship analyses. ART singletons with VTS were also more likely to be born preterm, although this difference did not reach statistical significance.

LIMITATIONS REASONS FOR CAUTION

We did not have information on maternal socio-economic status, but this factor is accounted for in the sibship analyses. We also had no information on whether fresh or frozen embryos were replaced.

WIDER IMPLICATIONS OF THE FINDINGS

The reduction in birth weight and increased risk of SGA in ART singletons with VTS may suggest the presence of harmful intrauterine factors with long-term health impact. While vanishing twins are not routinely observed in naturally conceived pregnancies, loss of a twin is potentially a risk factor for the surviving foetus in any pregnancy. This could be further explored in large samples of naturally conceived pregnancies with the necessary information.

STUDY FUNDING/COMPETING INTEREST(S)

The authors of this study are supported in part by the UK Medical Research Council, US National Institute of Environmental Health Sciences and the Norwegian Research Council. The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

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.

Assisted reproduction and risk of preterm birth in singletons by infertility diagnoses and treatment modalities: a population-based study

PURPOSE

The purpose of this study is to examine the spectrum of infertility diagnoses and assisted reproductive technology (ART) treatments in relation to risk of preterm birth (PTB) in singletons.

METHODS

Population-based assisted reproductive technology surveillance data for 2000-2010 were linked with birth certificates from three states: Florida, Massachusetts, and Michigan, resulting in a sample of 4,370,361 non-ART and 28,430 ART-related singletons. Logistic regression models with robust variance estimators were used to compare PTB risk among singletons conceived with and without ART, the former grouped by parental infertility diagnoses and treatment modalities. Demographic and pregnancy factors were included in adjusted analyses.

RESULTS

ART was associated with increased PTB risk across all infertility diagnosis groups and treatment types: for conventional ART, adjusted relative risks ranged from 1.4 (95% CI 1.0, 1.9) for male infertility to 2.4 (95% CI 1.8, 3.3) for tubal ligation. Adding intra-cytoplasmic sperm injection and/or assisted hatching to conventional ART treatment did not alter associated PTB risks. Singletons conceived by mothers without infertility diagnosis and with donor semen had an increased PTB risk relative to non-ART singletons.

CONCLUSIONS

PTB risk among ART singletons is increased within each treatment type and all underlying infertility diagnosis, including male infertility. Preterm birth in ART singletons may be attributed to parental infertility, ART treatments, or their combination.

Assisted Reproductive Technology and Newborn Size in Singletons Resulting from Fresh and Cryopreserved Embryos Transfer

OBJECTIVES AND STUDY DESIGN

The aim of this study was two-fold: to investigate the association of Assisted Reproductive Technology (ART) and small newborn size, using standardized measures; and to examine within strata of fresh and cryopreserved embryos transfer, whether this association is influenced by parental infertility diagnoses. We used a population-based retrospective cohort from Michigan (2000-2009), Florida and Massachusetts (2000-2010). Our sample included 28,946 ART singletons conceived with non-donor oocytes and 4,263,846 non-ART singletons.

METHODS

Regression models were used to examine the association of ART and newborn size, measured as small for gestational age (SGA) and birth-weight-z-score, among four mutually exclusive infertility groups: female infertility only, male infertility only, combined female and male infertility, and unexplained infertility, stratified by fresh and cryopreserved embryos transfer.

RESULTS

We found increased SGA odds among ART singletons from fresh embryos transfer compared with non-ART singletons, with little difference by infertility source [adjusted odds-ratio for SGA among female infertility only: 1.18 (95% CI 1.10, 1.26), male infertility only: 1.20 (95% CI 1.10, 1.32), male and female infertility: 1.18 (95% CI 1.06, 1.31) and unexplained infertility: 1.24 (95% CI 1.10, 1.38)]. Conversely, ART singletons, born following cryopreserved embryos transfer, had lower SGA odds compared with non-ART singletons, with mild variation by infertility source [adjusted odds-ratio for SGA among female infertility only: 0.56 (95% CI 0.45, 0.71), male infertility only: 0.64 (95% CI 0.47, 0.86), male and female infertility: 0.52 (95% CI 0.36, 0.77) and unexplained infertility: 0.71 (95% CI 0.47, 1.06)]. Birth-weight-z-score was significantly lower for ART singletons born following fresh embryos transfer than non-ART singletons, regardless of infertility diagnoses.

Increased risk of large-for-gestational age birthweight in singleton siblings conceived with in vitro fertilization in frozen versus fresh cycles

BACKGROUND

Children born from fresh in vitro fertilization (IVF) cycles are at greater risk of being born smaller and earlier, even when limited to singletons; those born from frozen cycles have an increased risk of large-for-gestational age (LGA) birthweight (z-score ≥1.28). This analysis sought to overcome limitations in other studies by using pairs of siblings, and accounting for prior cycle outcomes, maternal characteristics, and embryo state and stage.

METHODS

Pairs of singleton births conceived with IVF and born between 2004 and 2013 were identified from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System database, matched for embryo stage (blastocyst versus non-blastocyst) and infant gender, categorized by embryo state (fresh versus frozen) in 1st and 2nd births (four groups).

RESULTS

The data included 7795 singleton pairs. Birthweight z-scores were 0.00-0.04 and 0.24-0.26 in 1st and 2nd births in fresh cycles, and 0.25-0.34 and 0.50-0.55 in frozen cycles, respectively. LGA was 9.2-9.8 and 14.2-15.4% in 1st and 2nd births in fresh cycles, and 13.1-15.8 and 20.8-21.0% in 1st and 2nd births in frozen cycles. The risk of LGA was increased in frozen cycles (1st births, adjusted odds ratios (AOR) 1.74, 95% CI 1.45, 2.08; and in 2nd births when the 1st birth was not LGA, AOR 1.70, 95% CI 1.46, 1.98 for fresh/frozen and 1.40, 1.11, 1.78 for frozen/frozen).

CONCLUSIONS

Our results with siblings indicate that frozen embryo state is associated with an increased risk for LGA. The implications of these findings for childhood health and risk of obesity are unclear, and warrant further investigation.

Identifying Maternal Constraints on Fetal Growth and Subsequent Perinatal Outcomes Using a Multiple Embryo Implantation Model

Introduction

Although the majority of singleton births after in vitro fertilization (IVF) are uncomplicated, studies have suggested that IVF pregnancies may be independently associated with low birth weight (LBW), preterm birth (PTB), and perinatal mortality. These outcomes complicate multiple gestations as expected, but have also been reported in singletons. A multiple embryo implantation model allows for assessment of the early in utero environment, and therefore, assessment of any maternal constraints on developing fetuses. We question whether adverse perinatal outcomes associated with assisted reproductive techniques (ART) occur as a result of maternal physiologic adaptations.

Patients and Methods

This is a retrospective, single center study of ART cycles, specifically intracytoplasmic sperm injection (ICSI) cycles during a 16-year period. For each positive pregnancy test 9–11 days after embryo transfer, an ultrasonogram was performed at 7 weeks of gestation to record the number of implanted fetal poles with cardiac activity. Controlled ovarian stimulation (COS), hCG trigger, oocyte retrieval and sperm injection were performed as per our standard protocols. First trimester implantation sites that resulted in live births were defined as “true” to distinguish them from those that spontaneously reduced called “virtual.” Birth outcomes analyzed included birth weight and gestational age at delivery.

Results

A total of 17,415 cycles were analyzed. The average maternal age was 36.9 (±5.0) years. An overall fertilization rate of 73.4% generated approximately 48,708 good quality cleavage-stage embryos. In most patients (92.8%), an average of 3 embryos were transferred. The clinical pregnancy rate was 39.2% (n = 6,281). The overall occurrence of multiple gestations was 38.2% (n = 2,608) consisting of 2,038 twin, 511 triplet, and 59 quadruplet pregnancies. Of these multiple gestations, 18.6% of twin, 54.2% of triplet and 76.3% of quadruplet gestations spontaneously reduced. Failure of the implanted embryo to progress was not related to maternal age. Singleton newborns resulting from multiple implantation sites had lower birth weights (P<0.01) and shorter gestational ages (P<0.01) than those from a single implanted embryo. The number of embryos transferred did not affect the gestational length of singleton newborns. Although the birth weights of singletons from multiple implantation sites (virtual singletons) were lower than true singletons, the birth weight of virtual singletons were comparable to the birth weights of true twin, triplet, and quadruplet live births. Multiple logistic regression revealed that virtual singletons were an independent risk factor for PTB (odds ratio: 4.55, 95% CI 2.23–9.29) and LBW (odds ratio: 3.61, 95% CI 1.78–7.32), even after controlling for the number of oocytes, stimulation protocol type, sperm source, total gonadotropins administered, age, embryo quality, and day of embryo transfer.

Conclusions

Our study highlights that embryonic implantation sites during early gestation set the growth profile of each embryo, dictating later growth patterns. Specifically, spontaneous reduction of an embryo after multiple embryo implantations can confer greater perinatal risk in the form of LBW and PTB to the surviving fetus. Our findings suggest that maternal constraints or physiologic adaptations maybe one of the mechanisms mediating adverse perinatal outcomes when multiple embryo implantation occurs.

Risk of adverse pregnancy and perinatal outcomes after high technology infertility treatment: a comprehensive systematic review

In the literature, there is growing evidence that subfertile patients who conceived after infertility treatments have an increased risk of pregnancy and perinatal complications and this is particularly true for patients who conceived through use of high technology infertility treatments. Moreover, high technology infertility treatments include many concomitant clinical and biological risk factors. This review aims to summarize in a systematic fashion the current evidence regarding the relative effect of the different procedures for high technology infertility treatments on the risk of adverse pregnancy and perinatal outcome. A literature search up to August 2016 was performed in IBSS, SocINDEX, Institute for Scientific Information, PubMed, Web of Science and Google Scholar and an evidence-based hierarchy was used to determine which articles to include and analyze. Data on prepregnancy maternal factors, low technology interventions, specific procedures for male factor, ovarian tissue/ovary and uterus transplantation, and chromosomal abnormalities and malformations of the offspring were excluded. The available evidences were analyzed assessing the level and the quality of evidence according to the Oxford Centre for Evidence-Based Medicine guidelines and the Grading of Recommendations Assessment, Development, and Evaluation system, respectively. Current review highlights that every single procedure of high technology infertility treatments can play a crucial role in increasing the risk of pregnancy and perinatal complications. Due to the suboptimal level and quality of the current evidence, further well-designed studies are needed.

Prevalences and pregnancy outcome of vanishing twin pregnancies achieved by in vitro fertilization versus natural conception

OBJECTIVE

To evaluate whether vanishing twin (VT) pregnancies achieved by in vitro fertilization and intracytoplasmic sperm injection (IVF-ICSI) had a more adverse perinatal outcome than those after natural conception.

DESIGN

Longitudinal, retrospective cohort study.

SETTING

Tertiary university hospital.

PATIENT(S)

Three hundred and six (78 after IVF-ICSI and 228 after natural conception) VT pregnancies over a 22-year period, with VT cases matched to primarily singleton controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Obstetric and neonatal outcome data.

RESULT(S)

The incidence of VT was statistically significantly higher after natural conception (18.2% of twins) than after IVF-ICSI (12.6% of twins). The odds of VT in pregnancies complicated with pregestational or gestational diabetes were disproportionally higher in IVF-ICSI cases than in spontaneously conceived VT pregnancies (adjusted odds ratio [AOR]: 0.80 vs. 3.10 and 1.00 vs. 1.07, respectively). Previous induced abortion (AOR 1.34) or second-trimester fetal loss (AOR 3.3) increased the risk of VT pregnancies after spontaneous conception. Gestational diabetes mellitus in both the previous (AOR 5.41) and the present (AOR 2.3) pregnancy as well as chronic maternal diseases (AOR 3.5) and placentation anomalies all represented independent risk factors for VT after IVF-ICSI.

CONCLUSION(S)

Vanishing twin pregnancies had a lower prevalence and a worse perinatal outcome after IVF-ICSI as compared with those of their spontaneously conceived counterparts.

Singleton birthweight by gestational age following in vitro fertilization in the United States

BACKGROUND

Assisted reproductive technology has been reported to account for a disproportionate higher number of low birthweight infants, even in singleton births. Low birthweight infants occur from preterm birth, decreased intrauterine growth, or both. It is unclear whether infants conceived by in vitro fertilization (IVF) have a reduced intrauterine growth rate or intrauterine growth restriction. Growth-restricted newborns have higher perinatal morbidity and are at increased risk for adult-onset illnesses. To date, there are no national standards for birthweight percentiles by gestational week, allowing for fetal growth assessment of singletons conceived by assisted reproductive technology in the United States.

OBJECTIVE

The objective of the study was to establish US singleton IVF reference standards using birthweight percentiles by gestational age for singleton live births resulting from IVF in the United States.

STUDY DESIGN

We studied birthweight by completed weeks of gestation for 93,443 singleton IVF births reported to the Society for Assisted Reproductive Technologies, 2006-2010. The third to 97th birthweight percentiles per completed week of gestation for weeks between 24 and 42 were calculated and were compared with recently published birthweight percentiles by gestational age for 3,812,730 US singleton births in 2011.

RESULTS

Smoothed birthweight for gestational age charts and curves were created for all US IVF singletons and female-male singletons from 24 to 42 weeks. Over the span of 31-41 weeks of gestation, the 10th, 50th, and 90th birthweight percentile values of IVF singletons were comparable with recently published birthweight percentile values of US singletons. At 40 completed weeks of gestation, the 10th, 50th, and 90th birthweight percentiles of all IVF singletons were 3078, 3506, and 4053 g, as compared with corresponding 3005, 3499, and 4057 g of US singletons. The 10th, 50th, and 90th birthweight percentile values for female and male IVF singletons were also comparable with US female and male singletons.

CONCLUSION

Birthweight percentiles per completed week of gestation of IVF and US singletons are approximately equal from 31 until 41 completed weeks, suggesting that intrauterine growth is not reduced in IVF singleton infants.

Is the wrong question being asked in infertility research?

A persistent finding is that assisted reproductive technology (ART) is associated with compromised birth outcomes, including higher risks for prematurity, low birthweight, and congenital malformations, even among singletons. Over the past decade, our research group, the Massachusetts Outcome Study of Assisted Reproductive Technology (MOSART), has evaluated pregnancy and birth outcomes among three groups of women, those women treated with ART, those with indicators of subfertility but without ART treatment, and fertile women. We have also explored the influence of infertility-related diagnoses on outcomes for women and infants. Over the course of our research, we have changed our perspective from an original focus on ART treatment parameters as the primary cause of excess morbidity to one centered instead on the underlying infertility-related diagnoses. This paper summarizes the research findings from our group that support this change in focus for infertility-based research from a primary emphasis on ART treatment to greater attention to the contribution of preexisting pathology underlying the infertility and suggests directions for future analyses.

The MOSART database: linking the SART CORS clinical database to the population-based Massachusetts PELL reproductive public health data system

Although Assisted Reproductive Technology (ART) births make up 1.6 % of births in the US, the impact of ART on subsequent infant and maternal health is not well understood. Clinical ART treatment records linked to population data would be a powerful tool to study long term outcomes among those treated or not by ART. This paper describes the development of a database intended to accomplish this task. We constructed the Massachusetts Outcomes Study of Assisted Reproductive Technology (MOSART) database by linking the Society of Assisted Reproductive Technologies Clinical Outcomes Reporting System (SART CORS) and the Massachusetts (MA) Pregnancy to Early Life Longitudinal (PELL) data systems for children born to MA resident women at MA hospitals between July 2004 and December 2008. PELL data representing 282,971 individual women and their 334,152 deliveries and 342,035 total births were linked with 48,578 cycles of ART treatment in SART CORS delivered to MA residents or women receiving treatment in MA clinics, representing 18,439 eligible women of whom 9,326 had 10,138 deliveries in this time period. A deterministic five phase linkage algorithm methodology was employed. Linkage results, accuracy, and concordance analyses were examined. We linked 9,092 (89.7 %) SART CORS outcome records to PELL delivery records overall, including 95.0 % among known MA residents treated in MA clinics; 70.8 % with full exact matches. There were minimal differences between matched and unmatched delivery records, except for unknown residency and out-of-state ART site. There was very low concordance of reported use of ART treatment between SART CORS and PELL (birth certificate) data. A total of 3.4 % of MA children (11,729) were identified from ART assisted pregnancies (6,556 singletons; 5,173 multiples). The MOSART linked database provides a strong basis for further longitudinal ART outcomes studies and supports the continued development of potentially powerful linked clinical-public health databases.

Impact of single embryo transfer policy on perinatal outcomes in fresh and frozen cycles-analysis of the Japanese Assisted Reproduction Technology registry between 2007 and 2012

OBJECTIVE

To investigate whether the introduction of single embryo transfer (SET) policy in Japan has improved perinatal outcomes.

DESIGN

A retrospective cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 140,718 live births and 510 stillbirths (after 22 weeks of gestation) conceived by assisted reproductive technology in Japan between 2007 and 2012 were reviewed.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Preterm birth (PTB), low birth weight (LBW), very low birth weight (VLBW), small for gestational age (SGA), large for gestational age (LGA), perinatal mortality, and other pregnancy complications.

RESULT(S)

The rate of SET increased significantly from 52.2% in 2007 to 82.6% in 2012, while the rate of multiple pregnancy decreased significantly from 10.7% to 4.1% over the same period. The rates of PTB, LBW, and SGA decreased significantly, while that of LGA increased. Perinatal mortality decreased from 0.70% to 0.40% in fresh cycles, while that of frozen cycles did not change. Double ET or more was associated with a significantly increased risk for multiple pregnancy, placenta accreta, preterm premature rupture of membrane, cesarean section (CS), PTB, LBW, SGA, and early neonatal death compared with SET. Compared with before the SET policy was launched, the risks of multiple pregnancy, CS, early PTB before 32 weeks, LBW, VLBW, and SGA were significantly decreased after the policy was launched, with significant interactions of fresh/frozen status.

CONCLUSION(S)

The results suggest that the SET policy improved perinatal outcomes in Japan. The impact of SET policy was different in fresh and frozen cycles for several perinatal outcomes.

Adverse pregnancy outcomes after in vitro fertilization: effect of number of embryos transferred and plurality at conception

OBJECTIVE

To evaluate risks for adverse pregnancy outcomes by number of embryos transferred (ET) and fetal heartbeats (FHB) in assisted reproductive technology-conceived singleton live births.

DESIGN

Longitudinal cohort using cycles reported to the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System between 2004 and 2008 among women who were treated and gave birth in Massachusetts.

SETTING

Not applicable.

PATIENT(S)

Assisted reproductive technology data on 6,073 births between 2004 and 2008 were linked to vital records and hospital data. Likelihood of ET ≥3 vs. 1-2, FHB >1 vs. 1, and risks of preterm birth (PTB, <37 weeks' gestation), low birth weight (LBW, <2,500 g), and small-for-gestational-age birth weight (SGA, <10th percentile) with FHB >1 were modeled with binary logistic regression using a backward-stepping algorithm, and presented as adjusted odds ratios (95% confidence intervals).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

ET ≥3, FHB >1, PTB, LBW, and SGA.

RESULT(S)

Higher ET was significantly more likely with older maternal age, intracytoplasmic sperm injection, assisted hatching, cleavage-stage embryos, and thawed embryos. The likelihood of FHB >1 with ≥3 ET vs. 1-2 ET was 2.04 (1.68-2.48). Risks of PTB and LBW with FHB >1 were 1.63 (1.27-2.09) and 1.81 (1.36-2.39), respectively; the risk of SGA was not significant. Nulliparity was associated with higher risks of PTB (1.34 [1.12-1.59]), LBW (1.48 [1.20-1.83]), and SGA (2.17 [1.69-2.78]).

CONCLUSION(S)

Number of embryos transferred was strongly associated with FHBs, with twice the risk of FHB >1 with ≥3 ET vs. 1-2 ET. Increasing FHBs were associated with significantly greater risks for PTB and LBW outcomes.

Application of a validated prediction model for in vitro fertilization: comparison of live birth rates and multiple birth rates with 1 embryo transferred over 2 cycles vs 2 embryos in 1 cycle

OBJECTIVE

The purpose of this study was to use a validated prediction model to examine whether single embryo transfer (SET) over 2 cycles results in live birth rates (LBR) comparable with 2 embryos transferred (DET) in 1 cycle and reduces the probability of a multiple birth (ie, multiple birth rate [MBR]).

STUDY DESIGN

Prediction models of LBR and MBR for a woman considering assisted reproductive technology developed from linked cycles from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System for 2006-2012 were used to compare SET over 2 cycles with DET in 1 cycle. The prediction model was based on a woman's age, body mass index (BMI), gravidity, previous full-term births, infertility diagnoses, embryo state, number of embryos transferred, and number of cycles.

RESULTS

To demonstrate the effect of the number of embryos transferred (1 or 2), the LBRs and MBRs were estimated for women with a single infertility diagnosis (male factor, ovulation disorders, diminished ovarian reserve, and unexplained); nulligravid; BMI of 20, 25, 30, and 35 kg/m2; and ages 25, 35, and 40 years old by cycle (first or second). The cumulative LBR over 2 cycles with SET was similar to or better than the LBR with DET in a single cycle (for example, for women with the diagnosis of ovulation disorders: 35 years old; BMI, 30 kg/m2; 54.4% vs 46.5%; and for women who are 40 years old: BMI, 30 kg/m(2); 31.3% vs 28.9%). The MBR with DET in 1 cycle was 32.8% for women 35 years old and 20.9% for women 40 years old; with SET, the cumulative MBR was 2.7% and 1.6%, respectively.

CONCLUSION

The application of this validated predictive model demonstrated that the cumulative LBR is as good as or better with SET over 2 cycles than with DET in 1 cycle, while greatly reducing the probability of a multiple birth.

The type of culture medium and the duration of in vitro culture do not influence birthweight of ART singletons

STUDY QUESTION

Does the type of in vitro culture medium or the duration of in vitro culture influence singleton birthweight after IVF/ICSI treatment?

SUMMARY ANSWER

In a comparison of two culture media, neither the medium nor the duration of culture (Day 3 versus Day 5 blastocyst transfer) had any effect on mean singleton birthweight.

WHAT IS KNOWN ALREADY

Previous studies indicated that in vitro culture of human embryos may affect birthweight of live born singletons. Both the type of culture medium and the duration of culture may be implicated. However, these studies are small and report conflicting results.

STUDY DESIGN, SIZE, DURATION

A large retrospective analysis was performed including all singleton live births after transferring fresh Day 3 or Day 5 embryos. IVF and ICSI cycles performed between April 2004 and December 2009 at a tertiary care centre were included for analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 2098 singleton live births resulting from singleton pregnancies were included for analysis. Two different sequential embryo culture media were concurrently used in an alternating way: Medicult (n = 1388) and Vitrolife (n = 710). Maternal age, maternal and paternal BMI, maternal parity, maternal smoking, main cause of infertility, cycle rank, stimulation protocol, method of fertilization (IVF or ICSI), time in culture and number of embryos transferred were taken into account. Embryo transfers were performed either on Day 3 (n = 1234) or on Day 5 (n = 864). Singleton birthweight was the primary outcome parameter. Gestational age and gender of the newborn were accounted for in the multiple regression analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

No significant differences in mean singleton birthweight were observed between the two culture media: Medicult 3222 g (±15 SE) and Vitrolife 3251 g (±21 SE) (P = 0.264). The mean singleton birthweight was not different between Day 3 embryo transfers (3219 ± 16 g) and Day 5 blastocyst transfers (3250 ± 19 g; P = 0.209). Multiple regression analysis controlling for potential maternal, paternal, treatment and newborn confounders confirmed the non-significant differences in mean singleton birthweight between the two culture media. Likewise, the adjusted mean singleton birthweight was not different according to the duration of in vitro culture (P = 0.521).

LIMITATIONS, REASONS FOR CAUTION

The conclusions are limited by its retrospective design; however, the two different sequential culture systems were used in an alternating way during the same time period. Pregnancy-associated factors possibly influencing birthweight (such as diabetes, hypertension, pre-eclampsia) were not included in the analysis.

WIDER IMPLICATIONS OF THE FINDINGS

This large retrospective study does not support earlier concerns that both the type of culture medium and the duration of embryo culture influence singleton birthweight. However, a continuous surveillance of human embryo culture procedures (medium type, culture duration and other culture conditions) should remain a priority within assisted reproduction technology.

STUDY FUNDING/COMPETING INTERESTS

None.

The impact of assisted reproductive technologies on intra-uterine growth and birth defects in singletons

Pooled odds ratios from meta-analyses of infants born following assisted reproductive technologies (ART) compared with non-ART singletons show increases in low birth weight, preterm birth, small for gestational age, and birth defects. Although there have been small reductions in recent data, odds associated with these outcomes are still higher for ART singletons. Both ART procedures and underlying infertility contribute to these increased risks. Outcomes appear better for frozen-thawed compared with fresh embryo transfers, but are poorer than for non-ART infants. There is a concerning increase in large-for-gestational-age infants born following frozen-thawed embryo transfer and limited data on the effects of embryo vitrification used instead of slow-freezing techniques. Using large datasets, we now need to investigate risks of individual birth defects and disentangle the inter-related effects of different types of infertility and the multiple aspects of ART. Greater understanding of the causes of adverse ART outcomes and identification of modifiable risk factors may lead to further reductions in the disparities in outcome between ART and non-ART infants.

Calculating length of gestation from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) database versus vital records may alter reported rates of prematurity

OBJECTIVE

To compare length of gestation after assisted reproductive technology (ART) as calculated by three methods from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) and vital records (birth and fetal death) in the Massachusetts Pregnancy to Early Life Longitudinal Data System (PELL).

DESIGN

Historical cohort study.

SETTING

Database linkage analysis.

PATIENT(S)

Live or stillborn deliveries.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

ART deliveries were linked to live birth or fetal death certificates. Length of gestation in 7,171 deliveries from fresh autologous ART cycles (2004-2008) was calculated and compared with that of SART CORS with the use of methods: M1 = outcome date - cycle start date; M2 = outcome date - transfer date + 17 days; and M3 = outcome date - transfer date + 14 days + day of transfer. Generalized estimating equation models were used to compare methods.

RESULT(S)

Singleton and multiple deliveries were included. Overall prematurity (delivery <37 weeks) varied by method of calculation: M1 29.1%; M2 25.6%; M3 25.2%; and PELL 27.2%. The SART methods, M1-M3, varied from those of PELL by ≥ 3 days in >45% of deliveries and by more than 1 week in >22% of deliveries. Each method differed from each other.

CONCLUSION(S)

Estimates of preterm birth in ART vary depending on source of data and method of calculation. Some estimates may overestimate preterm birth rates for ART conceptions.

Factors associated with monozygosity in assisted reproductive technology pregnancies and the risk of recurrence using linked cycles

OBJECTIVE

To evaluate factors associated with monozygosity (MZ) (number of fetal heartbeats on early ultrasound greater than the number of embryos transferred) and the risk of recurrence in subsequent pregnancies using a national assisted reproduction database.

DESIGN

Historical cohort study.

SETTING

Clinic-based data.

PATIENT(S)

197,327 pregnancies (including 2,824 with evidence of MZ) from cycles reported to the Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) between 2004 and 2010.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Evidence of MZ, adjusted odds ratios and their 95% confidence intervals computed from logistic regression models.

RESULT(S)

In the univariate analysis, the risk of MZ was increased with ovulation disorders, donor oocytes, gonadotropin-releasing hormone agonist (GnRH-a) suppression, assisted hatching (AZH), and day 5-6 transfer, and was decreased with higher follicle-stimulating hormone (FSH) doses (≥3,000 IU). In the multivariate analysis, the risk of MZ was increased with GnRH-a suppression, AZH, and decreased with intracytoplasmic sperm injection (ICSI) and higher FSH dose. The interaction showed that although MZ was more likely with day 5-6 embryos, AZH had a minimal nonsignificant effect, whereas in day 2-3 embryos, AZH had a substantial statistically significant effect. Only one woman had a recurrence of MZ in a subsequent assisted reproduction pregnancy, which is consistent with randomness.

CONCLUSION(S)

The risk of MZ was higher with fresh day 5-6 embryos, donor oocytes, GnRH-a suppression, lower FSH doses, and AZH (particularly with day 2-3 embryos).

Low birth weight: is it related to assisted reproductive technology or underlying infertility?

Since 1978, we have witnessed a successful evolution of assisted reproductive technology (ART), with improvement of the pregnancy rates and a growing demand. However, in recent years, there has been increasing concern regarding its safety due to the potential health impact on its infants. The raise of the developmental origins of adult disease has positioned low birth weight (LBW) as a significant health issue. Although multiple studies have associated ART with LBW, the etiology of this association remains largely unknown. We review the potential association between different components of ART and infertility with LBW, while acknowledging the limitations of interpretation of the existing literature.

Why do singletons conceived after assisted reproduction technology have adverse perinatal outcome? Systematic review and meta-analysis

BACKGROUND

Assisted reproduction technology (ART) is used worldwide, at increasing rates, and data show that some adverse outcomes occur more frequently than following spontaneous conception (SC). Possible explanatory factors for the well-known adverse perinatal outcome in ART singletons were evaluated.

METHODS

PubMed and Cochrane databases from 1982 to 2012 were searched. Studies using donor or frozen oocytes were excluded, as well as those with no control group or including <100 children. The main outcome measure was preterm birth (PTB defined as delivery <37 weeks of gestation), and a random effects model was used for meta-analyses of PTB. Other outcomes were very PTB, low-birthweight (LBW), very LBW, small for gestational age and perinatal mortality.

RESULTS

The search returned 1255 articles and 65 of these met the inclusion criteria. The following were identified as predictors for PTB in singletons: SC in couples with time to pregnancy (TTP) > 1 year versus SC singletons in couples with TTP ≤ 1 year [adjusted odds ratio (AOR) 1.35, 95% confidence interval (CI) 1.22, 1.50]; IVF/ICSI versus SC singletons from subfertile couples (TTP > 1 year; AOR 1.55, 95% CI 1.30, 1.85); conception after ovulation induction and/or intrauterine insemination versus SC singletons where TTP ≤ 1 year (AOR 1.45, 95% CI 1.21, 1.74); IVF/ICSI singletons versus their non-ART singleton siblings (AOR 1.27, 95% CI 1.08, 1.49). The risk of PTB in singletons with a 'vanishing co-twin' versus from a single gestation was AOR of 1.73 (95% CI 1.54, 1.94) in the narrative data. ICSI versus IVF (AOR 0.80, 95% CI 0.69-0.93), and frozen embryo transfer versus fresh embryo transfer (AOR 0.85, 95% CI 0.76, 0.94) were associated with a lower risk of PTB.

CONCLUSIONS

Subfertility is a major risk factor for adverse perinatal outcome in ART singletons, however, even in the same mother an ART singleton has a poorer outcome than the non-ART sibling; hence, factors related to the hormone stimulation and/or IVF methods per se also may play a part. Further research is required into mechanisms of epigenetic modification in human embryos and the effects of cryopreservation on this, whether milder ovarian stimulation regimens can improve embryo quality and endometrial conditions, and whether longer culture times for embryos has a negative influence on the perinatal outcome.

Trends and correlates of good perinatal outcomes in assisted reproductive technology

OBJECTIVE

To estimate trends in good perinatal outcomes (singleton live births at term with birthweight more than 2,500 g) among live births after assisted reproductive technology in the United States from 2000 to 2008, and associated factors among singletons in 2008.

METHODS

Using retrospective cohort data from the National Assisted Reproductive Technology Surveillance System from 2000 to 2008, we calculated relative change and χ tests for trend in the proportion of good perinatal outcomes among assisted reproductive technology live births (n=444,909) and liveborn singletons (n=222,500). We conducted univariable analyses followed by multiple logistic regression to estimate the effects of various characteristics on the outcome among singletons born in 2008 after fresh, nondonor assisted reproductive technology cycles (n=20,780).

RESULTS

The proportion of good perinatal outcomes among all liveborn neonates increased from 38.6% in 2000 to 42.5% in 2008, whereas it declined marginally among singletons from 83.6% to 83.4%. One previous birth, transfer of fewer than three embryos, and the presence of fewer than three fetal hearts on 6-week ultrasound examination were associated with good perinatal outcome among singletons. Non-Hispanic black race, tubal factor infertility, uterine factor infertility, ovulatory disorder, and 5-day embryo culture were associated with reduced odds for a good outcome. The strongest association was the presence of one fetal heart compared with more than two (adjusted odds ratio 2.43, 95% confidence interval 1.73-3.42).

CONCLUSION

From 2000 to 2008, good perinatal outcomes increased among assisted reproductive technology live births. Among singleton live births, odds for good outcome were greatest with the presence of a single fetal heart and lowest in women of non-Hispanic black race.

LEVEL OF EVIDENCE

II.

Cerebral palsy and assisted conception

Assisted reproductive technologies have been widely used over the past 30 years, and 1% to 4% of births worldwide are products of these technologies. However, adverse health outcomes related to assisted reproductive technologies, including cerebral palsy, have been reported. We extracted and reviewed all relevant studies cited by Medline from 1996 to 2010 evaluating the role of assisted reproductive technologies as a causative factor for cerebral palsy and poor long-term neurologic outcome. The research suggests that multiple pregnancy, preterm delivery, and babies small for gestational age are factors in the development of cerebral palsy. The vanishing embryo syndrome may also play a role. We review the evidence for these potentially causative factors, as well as their implications for embryo transfer policies.

Is cryopreservation of embryos a legitimate surrogate marker of embryo quality in studies of assisted reproductive technology conducted using national databases?

OBJECTIVE

To investigate whether cryopreservation of supernumerary embryos is a good surrogate for embryo quality.

DESIGN

Retrospective study of 6,859 assisted reproductive technology (ART) cycles from women aged <35 years with two fresh day 3 embryos transferred.

SETTING

National Society for Assisted Reproductive Technology Clinic Outcome Reporting System data from 2006-2008.

PATIENT(S)

Women undergoing ART.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Embryo quality (good, fair, or poor), cell number, and live births were compared for cycles with and without cryopreservation, using χ(2) to evaluate statistical significance. The association of freezing with embryo quality was examined using multiple logistic regression after adjusting for confounders (patient age, oocyte yield, intracytoplasmic sperm injection [ICSI], assisted hatching, male factor infertility).

RESULT(S)

Cycles with cryopreservation were more likely to have two embryos of good quality transferred (81.3% vs. 48.5%) and had more 8-cell embryos transferred (76.0% vs. 50.1%). Relative to cycles with two good embryos (good-good), the adjusted odds ratios (OR) for cryopreservation were: good-fair (OR = 0.301, 95% confidence interval [CI] = 0.257-0.354), fair-fair (OR = 0.308, 95% CI = 0.258-0.367), and any poor (OR = 0.058, 95% CI = 0.040-0.083). The live birth rate was 52.4% for cycles with freezing and 40.6% for cycles without.

CONCLUSION(S)

Embryo quality and cell number were both associated with embryo cryopreservation. However, although cryopreservation was a strong marker for good quality, not having cryopreservation did not reliably indicate poor quality, as almost half of those cycles had two good quality embryos.

Ovarian stimulation and low birth weight in newborns conceived through in vitro fertilization

OBJECTIVE

Singleton neonates born after in vitro fertilization (IVF) are at increased risk for low birth weight, preterm delivery, or both. We sought to assess whether the alteration of the peri-implantation maternal environment resulting from ovarian stimulation may contribute to increased risk of low birth weight in IVF births.

METHODS

The Society for Assisted Reproductive Technologies database was used to identify IVF-conceived neonates born in the United States between 2004 and 2006. Associations were assessed in neonates born after fresh compared with frozen and thawed embryo transfer in women of similar ovarian responsiveness, in paired analysis of neonates born to the same woman after both types of embryo transfer, and in neonates born after oocyte donation.

RESULTS

Of 56,792 neonates identified, 38,626 and 18,166 were conceived after transfer of fresh and frozen embryos, respectively. In singletons, there was no difference in preterm delivery. However, the odds of overall low birth weight (10% compared with 7.2%; adjusted odds ratio [OR] 1.35; 95% confidence interval [CI] 1.20-1.51), low birth weight at term (2.5% compared with 1.2%, adjusted OR 1.73, 95% CI 1.31-2.29), and preterm low birth weight (34.1% compared with 23.8%, adjusted OR 1.49, 95% CI 1.24-1.78) were all significantly higher after fresh embryo transfer. In singletons, after either fresh or frozen embryo transfer in the same patient, this association was even stronger (low birth weight: 11.5% compared with 5.6%, adjusted OR 4.66, 95% CI 1.18-18.38). In oocyte donor recipients who do not undergo any ovarian hormonal stimulation for either a fresh or a frozen embryo transfer, no difference in low birth weight was demonstrated (11.5% compared with 11.3% adjusted OR 0.99, 95% CI 0.82-1.18).

CONCLUSION

The ovarian stimulation-induced maternal environment appears to represent an independent mediator contributing to the risk of low birth weight, but not preterm delivery, in neonates conceived after IVF.

LEVEL OF EVIDENCE

II.

National collection of embryo morphology data into Society for Assisted Reproductive Technology Clinic Outcomes Reporting System: associations among day 3 cell number, fragmentation and blastomere asymmetry, and live birth rate

OBJECTIVE

To evaluate the validity of collecting day 3 embryo morphology variables into the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System (SART CORS).

DESIGN

Retrospective.

SETTING

National database-SART CORS.

PATIENT(S)

Fresh autologous assisted reproductive technology (ART) cycles from 2006-2007 in which embryos were transferred singly (n=1,020) or in pairs (n=6,508) and embryo morphology was collected.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Relationship between live birth, maternal age, and morphology of transferred day 3 embryos as defined by cell number, fragmentation, and blastomere symmetry. Logistic multiple regressions and receiver operating characteristic curve analyses were applied to determine specificity and sensitivity for correctly classifying embryos as either failures or successes.

RESULT(S)

Live birth rate was positively associated with increasing cell number up to eight cells (<6 cells: 2.9%; 6 cells: 9.6%; 7 cells: 15.5%; 8 cells: 24.3%; and >8 cells: 16.2%), but was negatively associated with maternal age, increasing fragmentation, and asymmetry scores. An area under the receiver operating curve of 0.753 (95% confidence interval 0.740-0.766) was derived, with a sensitivity of 45.0%, a specificity of 83.2%, and 76.4% of embryos being correctly classified with a cutoff probability of 0.3.

CONCLUSION(S)

This analysis provides support for the validity of collecting morphology fields for day 3 embryos into SART CORS. Standardization of morphology collections will assist in controlling for embryo quality in future database analyses.

Toward understanding obstetrical outcome in advanced assisted reproduction: varying sperm, oocyte, and uterine source and diagnosis

OBJECTIVE

To evaluate the obstetrical outcome measures of birth weight (BW) and length of gestation (GA) in singleton pregnancies from in vitro fertilization (IVF), donor egg (DE), and gestational carrier (GC) cycles.

DESIGN

Retrospective data analysis.

SETTING

Clinics.

PATIENT(S)

SART data set from the years 2004-2006.

INTERVENTION(S)

The BW and GA of singleton pregnancies were compared in IVF, DE, and GA cycles.

MAIN OUTCOME MEASURE(S)

The BW and GA data were compared to evaluate the effects on these outcomes of the source of the egg, the uterus, or sperm or the primary reason given for treatment.

RESULT(S)

The mean BW and GA for DE cycles were 3,236 g and 37.4 weeks, respectively, which were less than those of IVF [3,265 g and 37.7 weeks]. GC BW was greater at 3,309 g with GA of 37.2 weeks. No difference was seen between donor or spouse sperm source; however, most female fertility-diagnosis cycles were associated with lower BW and GA than male factor-related cycles.

CONCLUSION(S)

Reduced BW and GA were observed for DE cycles versus IVF or GC cycles, suggesting that the uterine environment was more important to these outcomes than egg quality. Whereas altering the sperm source had no effect, female infertility diagnoses were associated with reductions in BW and GA.

Infant outcomes of assisted reproduction

Assisted reproductive technologies (ART) have become widely used in the treatment of subfertility over the last 30 years. Currently 1.7% of all births in the UK occur after assisted conception. This review summarises work that has been undertaken to investigate health outcomes of these children and summarises areas where uncertainty continues to exist. Much of the adverse health outcomes of children born after ART are related to higher order birth; however evidence suggests adverse perinatal outcomes in singletons as well as twins and triplets. The cause of adverse health outcomes in ART conceived children is as yet unclear and studies investigating causal factors such as underlying subfertility are discussed.