Consequences of vanishing twins in IVF/ICSI pregnancies

Pregnancy outcomes of monochorionic diamniotic and dichorionic diamniotic twin pregnancies conceived by assisted reproductive technology and conceived naturally: a study based on chorionic comparison

OBJECTIVE

To evaluate monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) twin pregnancies conceived by assisted reproductive technology (ART) and conceived naturally.

METHODS

We retrospectively analyzed the data on twin pregnancies conceived by ART from January 2015 to January 2022,and compared pregnancy outcomes of MCDA and DCDA twins conceived by ART with those of MCDA and DCDA twins conceived naturally, pregnancy outcomes between MCDA and DCDA twins conceived by ART, and pregnancy outcomes of DCT and TCT pregnancies reduced to DCDA pregnancies with those of DCDA pregnancies conceived naturally.

RESULT

MCDA pregnancies conceived by ART accounted for 4.21% of the total pregnancies conceived by ART and 43.81% of the total MCDA pregnancies. DCDA pregnancies conceived by ART accounted for 95.79% of the total pregnancies conceived by ART and 93.26% of the total DCDA pregnancies. Women with MCDA pregnancies conceived by ART had a higher premature delivery rate, lower neonatal weights, a higher placenta previa rate, and a lower twin survival rate than those with MCDA pregnancies conceived naturally (all p < 0.05). Women with DCDA pregnancies conceived naturally had lower rates of preterm birth, higher neonatal weights, and higher twin survival rates than women with DCDA pregnancies conceived by ART and those with DCT and TCT pregnancies reduced to DCDA pregnancies (all p < 0.05).

CONCLUSION

Our study confirms that the pregnancy outcomes of MCDA pregnancies conceived by ART are worse than those of MCDA pregnancies conceived naturally. Similarly, the pregnancy outcomes of naturally-conceived DCDA pregnancies are better than those of DCDA pregnancies conceived by ART and DCT and TCT pregnancies reduced to DCDA pregnancies.

Placental, maternal, fetal, and technical origins of false-positive cell-free DNA screening results

The introduction of noninvasive prenatal testing has resulted in substantial reductions to previously accepted false-positive rates of prenatal screening. Despite this, the possibility of false-positive results remains a challenging consideration in clinical practice, particularly considering the increasing uptake of genome-wide noninvasive prenatal testing, and the subsequent increased proportion of high-risk results attributable to various biological events besides fetal aneuploidy. Confined placental mosaicism, whereby chromosome anomalies exclusively affect the placenta, is perhaps the most widely accepted cause of false-positive noninvasive prenatal testing. There remains, however, a substantial degree of ambiguity in the literature pertaining to the clinical ramifications of confined placental mosaicism and its potential association with placental insufficiency, and consequentially adverse pregnancy outcomes including fetal growth restriction. Other causes of false-positive noninvasive prenatal testing include vanishing twin syndrome, in which the cell-free DNA from a demised aneuploidy-affected twin triggers a high-risk result, technical failures, and maternal origins of abnormal cell-free DNA such as uterine fibroids or unrecognized mosaicisms. Most concerningly, maternal malignancies are also a documented cause of false-positive screening results. In this review, we compile what is currently known about the various causes of false-positive noninvasive prenatal testing.

Association Between Assisted Reproductive Technology and Cerebral Palsy: A Meta-Analysis

BACKGROUND

Since 1978 many children are born thanks to assisted reproductive technology (ART). However, the long-term effects of these therapies are still not fully known. Our objective is to evaluate the risk of cerebral palsy (CP) after ART compared with that in those spontaneously conceived (SC) and to examine this risk in single, multiple, and preterm births and the evolution of the risk over the years.

METHODS

PubMed, Embase, and Web of Science databases were searched until December 2022. Studies were included if they studied CP cases in children born through ART. 16 studies were finally selected. Quality of studies was assessed using Newcastle Ottawa Scale. Pooled OR was estimated by weighting individual OR/RR by the inverse of their variance. A random-effect model was applied. To assess the causes of heterogeneity, we performed meta-regression analyses.

RESULTS

A significantly high risk of CP was found (OR = 1.27; 95% CI 1.12 to 1.43) in children born through ART compared with those SC. This risk increased in singletons (OR = 1.48; 95% CI 1.23 to 1.79) but disappeared in multiple (OR = 1.05; 95% CI 0.93 to 1.18) and preterm births (OR = 1.09; 95% CI 0.87 to 1.37). We found a higher risk of CP in children born before the year 2000 (OR = 3.40; 95% CI 2.49 to 4.63).

CONCLUSIONS

ARTs slightly increase the risk of CP once the effect of multiple gestation is controlled. Further studies are needed to clarify whether the techniques themselves, fertility problems, or associated maternal comorbidities are responsible for this risk.

Twin Gestation With Spontaneous Reduction To Singleton

Twin gestations are at increased risk of single intrauterine fetal death. A first-trimester loss is a common complication in twin gestations. The rate of co-twin morbidity and mortality is higher when a single demise occurs in the second and third trimesters. Monochorionicity strongly influences the prognosis for the surviving co-twin. Fetal ultrasound combined with MRI may be able to help predict neurological injury to the surviving co-twin. The rate of co-twin demise decreases with advancing gestation. After single intrauterine fetal demise, monochorionic gestations should be delivered by 34 weeks and dichorionic by 36 to 37 weeks gestation.

Subfertility versus ART: unraveling the origins of fetal cardiac programming

STUDY QUESTION

Do spontaneously conceived (SC) fetuses from subfertile couples show the same signs of cardiac remodeling as those observed after IVF treatments?

SUMMARY ANSWER

As opposed to fetuses from IVF, SC fetuses from subfertile couples do not show cardiac remodeling and present a similar cardiac structure and function to those of SC fetuses from fertile couples.

WHAT IS KNOWN ALREADY

Subjects conceived by IVF present signs of cardiac remodeling and suboptimal function in utero and during childhood, including larger atria, more globular and thicker ventricles, reduced longitudinal motion, and impaired relaxation as compared to SC individuals from fertile couples. There are no previous publications investigating the independent cardiac programming effects of infertility in SC fetuses from subfertile couples (with time-to-pregnancy (TTP) over 12 months).

STUDY DESIGN, SIZE, DURATION

A prospective cohort study of 289 singleton pregnancies exposed and not exposed to subfertility recruited from 2019 to 2021, including 96 SC pregnancies from fertile couples (TTP under 12 months), 97 SC from subfertile couples (TTP over 12 months), and 96 from IVF after fresh embryo transfer. Fetal echocardiography was performed in all pregnancies. Epidemiological data and perinatal outcomes were collected in all pregnancies. The overall attrition rate was 15.7%.

PARTICIPANTS/MATERIALS, SETTING, METHODS

SC from subfertile couples and IVF pregnancies were identified as eligible at pregnancy diagnosis, and eligible SC pregnancies from fertile couples who attended our maternal-fetal unit were invited to participate at third trimester, being matched to the other groups by maternal age. Fetal echocardiography was performed at 29-34 weeks of pregnancy to assess cardiac structure and function, and results were adjusted by parental age, maternal smoking status, child's birth order, birthweight centile, gestational age, and estimated fetal weight at scan.

MAIN RESULTS AND THE ROLE OF CHANCE

Parental age, ethnicity, BMI, and smoking exposure, median gestational age and estimated fetal weight were similar in all study groups. There were no significant differences in infertility duration or etiology between the subfertile and the IVF populations (TTP: subfertile median 35 months (interquartile range 20-48) versus IVF: 47 (25-61); P-value = 0.051). While both fertile and subfertile SC groups presented similar fetal cardiac results, IVF fetuses showed larger atria (right atria-to-heart ratio: IVF mean 18.9% (SD 3.4) versus subfertile 17.8% (3.5) versus fertile 17.6% (3.3); adjusted P-value < 0.001), more globular ventricles (right ventricular sphericity index: IVF 1.56 (0.25) versus subfertile 1.72 (0.26) versus fertile 1.72 (0.26); <0.001), and thicker myocardial walls (relative wall thickness: IVF 0.86 (0.22) versus subfertile 0.64 (0.13) versus fertile 0.64 (0.18); <0.001). Whereas SC fetuses from fertile and subfertile couples had preserved cardiac function, IVF fetuses showed signs of suboptimal systolic and diastolic function, with reduced tricuspid ring displacement (IVF 7.26 mm (1.07) versus subfertile 8.04 mm (1.18) versus fertile 7.89 mm (1.51); <0.001) and increased left myocardial performance index (IVF 0.49 (0.08) versus subfertile 0.45 (0.09) versus fertile 0.45 (0.10); <0.001). A sub-analysis including only unexplained infertility cases in subfertile SC and IVF groups showed similar results.

LIMITATIONS, REASONS FOR CAUTION

The fetal cardiac changes reported here are subclinical, and most of the cardiovascular parameters were within normal ranges. Although echocardiographic changes are recognized as potential cardiovascular risk factors, their association with long-term cardiovascular disease remains to be demonstrated.

WIDER IMPLICATIONS OF THE FINDINGS

Subfertility per se does not seem to be associated to fetal cardiac remodeling, which has been previously described in IVF fetuses. Future studies are warranted to further investigate other factors related to the observed fetal cardiac changes associated with ART.

STUDY FUNDING/COMPETING INTEREST(S)

This project has been partially funded with support from the Erasmus + Programme of the European Union (Framework Agreement number: 2013-0040). This publication reflects the views only of the author, and the Commission cannot be held responsible for any use, which may be made of the information contained therein. Additionally, the research leading to these results has received funding from 'la Caixa' Foundation under grant agreement LCF/PR/GN18/10310003, the Instituto de Salud Carlos III (PI15/00130, PI16/00861, PI17/00675, PI18/00073, INT21/00027)-co-funded by the European Union, Cerebra Foundation for the Brain Injured Child (Carmarthen, Wales, UK) and AGAUR 2017 SGR grant no 1531. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Pregnancy and neonatal outcomes of monozygotic twins resulting from assisted reproductive technology: a 10-year retrospective study

BACKGROUND

Monozygotic twins (MZTs) are associated with high risks of maternal and fetal complications. Even with the widely used elective single embryo transfer (SET), the risk of MZTs following assisted reproductive technology (ART) treatments remains. However, most studies of MZTs focused on the relevant etiology, with few studies describing pregnancy and neonatal outcomes.

METHODS

This retrospective cohort study included 19,081 SET cycles resulting from in-vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), preimplantation genetic testing (PGT) and testicular sperm aspiration (TESA) performed between January 2010 and July 2020 in a single university-based center. A total of 187 MZTs were included in this investigation. The main outcome measures were the incidence, pregnancy and neonatal outcomes of MZTs. Multivariate logistic regression analysis was performed to figure out the risk factors for pregnancy loss.

RESULTS

The overall rate of MZTs from ART treatment in SET cycles was 0.98%. No significant difference was found in the incidence of MZTs among the four groups (p = 0.259). The live birth rate of MZTs in the ICSI group (88.5%) was significantly more favorable than in the IVF, PGT and TESA groups (60.5%, 77.2% and 80%, respectively). IVF resulted in a significantly increased risk of pregnancy loss (39.4%) and early miscarriage (29.5%) in MZT pregnancies compared to ICSI (11.4%, 8.5%), PGT (22.7%, 16.6%) and TESA (20%, 13.3%). The total rate of twin-to-twin transfusion syndrome (TTTS) in MZTs was 2.7% (5/187); however, the TESA group had the highest rate at 20% and was significantly higher than the PGT group (p = 0.005). The four ART groups had no significant effect on the occurrence of congenital abnormalities or other neonatal outcomes in newborns from MZT pregnancies. Multivariate logistic regression analysis revealed that infertility duration, cause of infertility, the total dose of Gn used, history of miscarriages, and the number of miscarriages were not related to the risk of pregnancy loss (p > 0.05).

CONCLUSIONS

The rate of MZTs was similar among the four ART groups. The pregnancy loss and the early miscarriage rate of MZTs was increased in IVF patients. Neither the cause of infertility nor the history of miscarriage was correlated with the risk of pregnancy loss. MZTs in the TESA group had a higher risk of TTTS, placental effects influenced by sperm and paternally expressed genes may play a role. However, due to the small total number, studies with larger sample sizes are still needed to validate these result. Pregnancy and neonatal outcomes of MZTs after PGT treatment seem to be reassuring but the duration of the study was short, and long-term follow-up of the children is needed.

Effects of parity on preterm delivery in twin gestations conceived with in vitro fertilization

Objective

To determine the relationship between prior obstetrical history and gestational age at delivery in a twin pregnancy.

Design

Retrospective cohort study using the United States Society for Assisted Reproductive Technology Clinic Outcomes Reporting System database.

Setting

Clinic-based data.

Patients

Patients undergoing in vitro fertilization (IVF) in the United States with live delivery of twins.

Interventions

None.

Main outcome measures

The main outcome measures are median gestational age at delivery and rate of preterm delivery (before 37 weeks).

Results

The median gestational age at delivery of IVF-conceived twins was 36.3 (interquartile rate 34.4, 37.6) weeks for nulliparous women, 35.9 (34.0, 37.1) weeks for parous women with a prior preterm birth, and 36.7 (35.1, 37.7) weeks for parous women without a prior preterm birth. The rate of preterm delivery was 61% for nulliparous women, 70% for parous women with a prior preterm birth, and 55% for parous women without a prior preterm birth.

Conclusions

Parous women without a history of preterm delivery had lower rates of preterm delivery in a subsequent twin pregnancy than nulliparous women. Nulliparous women had lower rates of preterm delivery compared with parous women with a history of preterm delivery.

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

RESEARCH QUESTION

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

DESIGN

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

RESULTS

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

CONCLUSION

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

Obstetric and Perinatal Outcomes of Singleton Births Following Single- vs Double-Embryo Transfer in Sweden

Importance

Pregnancies resulting from assisted reproductive technology are associated with an increased risk of adverse perinatal outcomes compared with those following natural conception. Previous studies have shown an association of pregnancies resulting from transfer of multiple embryos with these negative findings.

Objective

To determine the risk for adverse outcomes in singletons conceived through assisted reproduction using double-embryo transfer (DET) vs single-embryo transfer (SET).

Design, Setting, and Participants

This cohort study used data from women who achieved singleton deliveries after SET or DET in Sweden between 2007 and 2017 as recorded in the National Quality Registry for Assisted Reproduction. All embryo transfers, at cleavage or blastocyst stage, replaced in fresh or frozen treatment cycles were included. Data on obstetric and neonatal outcomes were retrieved by linkage to the National Medical Birth Register. Naturally conceived singletons were included as a reference group. Data were analyzed between September 2021 and August 2022.

Exposures

Double-embryo transfer leading to singleton birth.

Main Outcomes and Measures

Relative risk ratios or odds ratios (ORs) and absolute risk differences (ARDs) in percentage points with 95% CIs were calculated for obstetric and perinatal outcomes in singleton births conceived using DET vs SET.

Results

Among 1 115 863 singleton births, 30 713 singletons were born after SET and 5123 after DET. A higher risk of neonatal death was found in singletons after DET vs SET (OR, 2.67 [95% CI, 1.28-5.55]; ARD, 0.2 percentage points [95% CI, 0.0-0.4 percentage points]). In frozen embryo transfers, DET was associated with a higher risk of low birth weight (OR, 1.64 [95% CI, 1.19-2.25]; ARD, 2.0 percentage points [95% CI, 0.5-3.5 percentage points]). Among blastocyst transfers, DET was associated with very preterm birth (relative risk ratio, 2.64 [95% CI, 1.50-4.63]; ARD, 1.8 percentage points [95% CI, 0.3-3.4 percentage points]) and low birth weight (OR, 1.83 [95% CI, 1.29-2.60]; ARD, 3.2 percentage points [95% CI, 0.9-5.5 percentage points]).

Conclusions and Relevance

These results indicate a higher risk of adverse outcomes following DET, even when the result is a singleton birth, vs singletons born after SET. Adverse outcomes were mainly observed in singletons following DET using frozen embryos and blastocysts.

Noninvasive Prenatal Screening for Trisomy 21 in Patients with a Vanishing Twin

A vanishing twin (VT) occurs in up to 30% of early diagnosed twin pregnancies and is associated with an increased risk of fetal aneuploidy. Here, we describe our experience in a large VT population of 847 patients that underwent noninvasive prenatal testing (NIPT) for common fetal trisomies over a three-year period. All patients underwent an ultrasound examination prior to NIPT. Two comparison populations were included, namely, the singleton (n = 105,560) and the viable multiple gestation pregnancy samples (n = 9691) collected over the same period. All NIPT samples in the VT population received a result, of which 14 were high-risk for trisomy 21 (1.6%), nine for trisomy 18 (1.1%), and six for trisomy 13 (0.7%). Diagnostic testing confirmed the presence of trisomy 21 in 6/12 samples, giving a positive predictive value of 50%. One trisomy 18 case and no trisomy 13 cases were confirmed. The time between fetal demise and NIPT sampling did not appear to affect the number of true- or false-positive cases. In conclusion, NIPT is an effective screening method for trisomy 21 in the surviving fetus(es) in VT pregnancies. For trisomies 18 and 13, a positive NIPT should be interpreted carefully and ultrasound monitoring is preferrable over invasive diagnostic testing.

Single-embryo transfer implies quality of care in reproductive medicine

This review appraises evidence on the difference between single- and double-embryo transfer (SET, DET) in assisted reproductive technology (ART) regarding the four healthcare quality dimensions most important to fertility patients and doctors. Regarding safety, not only does DET create the uncontested perinatal risks of twin pregnancies, but compelling evidence has added that singleton pregnancies after a vanishing twin also have poorer perinatal outcomes. SET is as effective as DET, as shown by meta-analyses of randomized controlled trials, comparing two cycles of SET versus DET and shown by cumulative live birth rates of entire ART trajectories of up to six cycles. Proposing SET, which is safer than DET and as effective, as the gold standard is not irreconcilable with patient-centred care if patients are thoroughly informed on the reasoning behind the proposition and welcomed to challenge whether it fits their personal values. The cost-efficiency of SET is clearly higher, which has even induced certain countries to start reimbursing ART on the condition that SET is used. In conclusion, SET should be the gold standard offered to all patients. The question is not whether to apply SET but how to apply it in terms of patient selection, patient-centred counselling and coverage of treatment.

The Impact of Assisted Hatching on Monozygotic Twinning is Related to Female Age and Insemination Method: A New Perspective

Whether assisted hatching (AH) is associated with a higher incidence of monozygotic twinning (MZT) in women undergoing assisted reproductive technology remains controversial; the aim of the study was to demonstrate the relationship between AH and MZT. A total of 8900 clinical pregnancies were selected among embryo transfer cycles from January 2011 to October 2019. Women receiving day (D) 3 embryos were divided into groups A-C: group A (n = 1651) and group B (n = 1045) included women aged ≤37 or ≥38 years, respectively, with zona pellucida (ZP) thinning; group C (n = 3865) included women aged ≤37 years without AH. Women aged ≤37 years who underwent blastocyst transfer and/or blastocyst ZP breaching were included in group D (n = 2339). The incidence of MZT was compared among groups A, B and C, and between groups C and D. The incidence of MZT in group B (2.2%) was significantly higher than in group A (1.0%), especially following intracytoplasmic sperm injection (ICSI), while the incidence of MZT in group A (1.0%) was significantly lower than in group C (2.2%). The MZT rate with in vitro fertilization was higher in group D (2.8%) than in group C (2.2%), but the MZT rate following ICSI was not significantly different between the two groups. ZP thinning of D3 embryos may increase the risk of MZT in older women (≥38 years), but decrease it in younger women (≤37 years). ZP breaching may be useful to reduce the incidence of MZT in ICSI-generated blastocysts.

The clinical outcomes of selective and spontaneous fetal reduction of twins to a singleton pregnancy in the first trimester: a retrospective study of 10 years

BACKGROUND

Singleton pregnancy is encouraged to reduce pregnancy complications. In addition to single embryo transfer (SET), selective and spontaneous fetal reduction (SEFR and SPFR) can also achieve singleton pregnancies. After SEFR or SPFR, an inanimate fetus remains in the uterus. It is unclear whether the inanimate fetus would adversely affect another fetus or the mother. Previous studies have focused on the differences between pre- and post-reduction. However, studies focusing on the influence of SEFR and SPFR on the remaining fetal development and maintenance of pregnancy are rare.

METHODS

Materials from 5922 patients whose embryo transfer dates ranged from March 2011 to January 2021 were collected. Both the SEFR group (n = 390) and SPFR group (n = 865) had double embryos transferred (DET) and got twin pregnancies, but subsequent selective or spontaneous fetal reduction occurred. The SET group (n = 4667) had only one embryo transferred. All were singleton pregnancies on the 65th day after embryo transfer. Clinical outcomes, including pregnancy outcomes, pregnancy complications, and newborn outcomes, were compared among the three groups.

RESULTS

After adjusting for age, infertility duration, types of infertility, states of embryos, body mass index, and factors affecting SET or DET decisions, multivariate regression analysis revealed that SEFR increased the risk of miscarriage (OR 2.368, 95% CI 1.423-3.939) and preterm birth (OR 1.515, 95% CI 1.114-2.060), and reduced the gestational age (βeta -0.342, 95% CI -0.544- -0.140). SPFR increased the risk of gestational diabetes mellitus (GDM) (OR 1.657, 95% CI 1.215-2.261), preterm premature rupture of membranes (PPROM) (OR 1.649, 95% CI 1.057-2.574), and abnormal amniotic fluid volume (OR 1.687, 95% CI 1.075-2.648). Both SEFR and SPFR were associated with reduced live birth rate (OR 0.522, 95% CI 0.330-0.825; OR 0.671, 95% CI 0.459-0.981), newborn birth weight (βeta -177.412, 95% CI -235.115--119.709; βeta -42.165, 95% CI -83.104--1.226) as well as an increased risk of low-birth-weight newborns (OR 2.222, 95% CI 1.490-3.313; OR 1.510, 95% CI 1.092-2.087).

CONCLUSIONS

DET with subsequent fetal reduction was related to poor clinical outcomes. We recommend that DET with subsequent fetal reduction should only be considered as a rescue method for multiple pregnancy patients with potential complications, and SET is more advisable.

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.

Multiple gestation associated with infertility therapy: a committee opinion

This Committee Opinion provides practitioners with suggestions to reduce the likelihood of iatrogenic multiple gestation resulting from infertility treatment. This document replaces the document of the same name previously published in 2012 (Fertil Steril 2012;97:825-34 by the American Society for Reproductive Medicine).

The Influence of the Vanishing Twin on the Perinatal Outcome of Surviving Singleton in IVF Pregnancy

OBJECTIVE

The purpose of this study was to clarify the influence of the vanishing twin (VT) on the perinatal outcomes in the surviving singleton and further identify the susceptible window.

STUDY DESIGN

Retrospective cohort study.

METHODS

A total of 636 survivors of a vanished co-twin and 11,148 singleton controls were enrolled. The exposed group was further divided into early VT (EVT, VT ≤13 weeks, N = 593) and late VT subgroups (LVT, VT >13 weeks, N = 43) according to the gestational age of the twin vanishing. All participants were conceived through in vitro fertilization (IVF). Perinatal outcomes including gestational age, birthweight, and the incidence of preterm birth (PTB), low birthweight (LBW), small for gestational age (SGA), neonatal intensive care unit (NICU) admission, umbilical cord abnormality, jaundice of the newborn, and oligohydramnios were compared among the groups.

RESULTS

In our birth cohort, about 5.4% of all singleton deliveries originated from vanishing twin pregnancies. Compared with the singletons, both early and late VT pregnancy had a significantly lower birth weight (3337.57±532.24 g and 2916.05±526.07 g vs. 3446.15±526.07 g; p < 0.001 and p < 0.001), more frequent neonatal jaundice (47.0% and 60.5% vs. 40.6%; p = 0.002 and p = 0.008), and decreased incidence of umbilical cord abnormality (15.5% and 7.0% vs. 19.9%; p = 0.009 and p = 0.034). Newborns in the early VT group were more likely to manifest as SGA (5.4% vs. 3.6%, p = 0.002) and suffered oligohydramnios (5.4% vs. 3.4%; p = 0.008) than the primary singletons. In addition, the gestational age of late VT survivors was shorter than that of the controls (37.25 ± 3.25 vs. 39.04 ± 1.63, p = 0.001) and had a significantly higher risk of PTB (30.2% vs. 6.6%; p < 0.001) and NICU admission (27.9% vs. 9.4%, p < 0.001). All differences except for SGA maintain significance after adjusting for maternal age, BMI, and parity.

CONCLUSIONS

Singletons with a vanished co-twin had worse perinatal outcomes compared with the original singletons, with LVT burden even much on the survival one. Therefore, close monitoring during the perinatal period was suggested in this type of neonates. Moreover, elective single embryo transfer should also be fully considered which could tackle the problem at its root.

Neurodevelopmental outcomes of preterm infants conceived by assisted reproductive technology

BACKGROUND

There have been concerns about the development of children conceived through assisted reproductive technology. Despite multiple studies investigating the outcomes of assisted conception, data focusing specifically on the neurodevelopmental outcomes of infants conceived through assisted reproductive technology and born preterm are limited.

OBJECTIVE

This study aimed to evaluate and compare the neurodevelopmental outcomes of preterm infants born at <29 weeks' gestation at 18 to 24 months' corrected age who were conceived through assisted reproductive technology and those who were conceived naturally.

STUDY DESIGN

This retrospective cohort study included inborn, nonanomalous infants, born at <29 weeks' gestation between January 1, 2010, and December 31, 2016, who had a neurodevelopmental assessment at 18 to 24 months' corrected age at any of the 10 Canadian Neonatal Follow-Up Network clinics. The primary outcome was neurodevelopmental impairment at 18 to 24 months, defined as the presence of any of the following: cerebral palsy; Bayley-III cognitive, motor, or language composite score of <85; sensorineural or mixed hearing loss; and unilateral or bilateral visual impairment. Secondary outcomes included mortality, composite of mortality or neurodevelopmental impairment, significant neurodevelopmental impairment, and each component of the primary outcome. We compared outcomes between infants conceived through assisted reproductive technology and those conceived naturally, using bivariate and multivariable analyses after adjustment.

RESULTS

Of the 4863 eligible neonates, 651 (13.4%) were conceived using assisted reproductive technology. Maternal age; education level; and rates of diabetes mellitus, receipt of antenatal corticosteroids, and cesarean delivery were higher in the assisted reproduction group than the natural conception group. Neonatal morbidity and death rates were similar except for intraventricular hemorrhage, which was lower in the assisted reproduction group (33% [181 of 546] vs 39% [1284 of 3318]; P=.01). Of the 4176 surviving infants, 3386 (81%) had a follow-up outcome at 18 to 24 months' corrected age. Multivariable logistic regression adjusting for gestational age, antenatal steroids, sex, small for gestational age, multiple gestations, mode of delivery, maternal age, maternal education, pregnancy-induced hypertension, maternal diabetes mellitus, and smoking showed that infants conceived through assisted reproduction was associated with lower odds of neurodevelopmental impairment (adjusted odds ratio, 0.67; 95% confidence interval, 0.52-0.86) and the composite of death or neurodevelopmental impairment (adjusted odds ratio, 0.67; 95% confidence interval, 0.54-0.84). Conception through assisted reproductive technology was associated with decreased odds of a Bayley-III composite cognitive score of <85 (adjusted odds ratio, 0.68; 95% confidence interval, 0.48-0.99) and composite language score of <85 (adjusted odds ratio, 0.67; 95% confidence interval, 0.50-0.88).

CONCLUSION

Compared with natural conception, assisted conception was associated with lower odds of adverse neurodevelopmental outcomes, especially cognitive and language outcomes, at 18 to 24 months' corrected age among preterm infants born at <29 weeks' gestation. Long-term follow-up studies are required to assess the risks of learning disabilities and development of complex visual-spatial and processing skills in these children as they reach school age.

Cerebral palsy in ART children has declined substantially over time: a Nordic study from the CoNARTaS group

STUDY QUESTION

Are the decreasing multiple birth rates after ART associated with a simultaneous drop in the incidence of cerebral palsy (CP) in ART children over time?

SUMMARY ANSWER

The relative odds of CP in ART children have declined in the Nordic countries over the past two decades concurrently with declining multiple birth rates.

WHAT IS KNOWN ALREADY

In the Nordic countries, the rate of twin pregnancies after ART has decreased from 30% in the early 1990s to 4-13% in 2014, following the implementation of elective single embryo transfer (SET). Consequently, preterm birth rates have declined substantially in ART pregnancies. However, whether the risk of CP, a known consequence of preterm birth, has decreased correspondingly is still unknown.

STUDY DESIGN, SIZE, DURATION

Retrospective register-based cohort study based on data on all singletons, twins, and higher-order multiples born in Denmark (birth year 1994-2010), Finland (1990-2010), and Sweden (1990-2014), corresponding to 111 844 ART children and 4 679 351 spontaneously conceived children.

PARTICIPANTS/MATERIAL, SETTING, METHODS

Data were obtained from a large Nordic cohort of children born after ART and spontaneous conception initiated by the Committee of Nordic ART and Safety-CoNARTaS. The CoNARTaS cohort was established by cross-linking national register data using the unique personal identification number, allocated to every citizen in the Nordic countries. Data from the National Medical Birth Registers, where information on maternal, obstetric, and perinatal outcomes is recorded, were cross-linked to data from the National ART- and Patients Registers to obtain information on fertility treatments and CP diagnoses. Relative risks of CP for ART compared to spontaneous conception were estimated as odds ratios from multivariate logistic regression analyses across all birth years, as well as for the following birth year categories: 1990-1993, 1994-1998, 1999-2002, 2003-2006, 2007-2010, and 2011-2014. Analyses were made for all children and for singletons and twins, separately.

MAIN RESULTS AND THE ROLE OF CHANCE

The main outcome measure was the relative odds of CP in different time periods for ART versus spontaneously conceived children. CP was diagnosed in 661 ART children and 16 478 spontaneously conceived children born between 1990 and 2014. In 1990-1993, the relative odds of CP were substantially higher in all ART children (adjusted odds ratio (aOR) 2.76 (95% CI 2.03-3.67)) compared with all spontaneously conceived children, while in 2011-2014, it was only moderately higher (aOR 1.39 (95% CI 1.01-1.87)). In singletons, the higher relative odds of CP in ART children diminished over time from 1990 to 1993 (aOR 2.02 (95% CI 1.22-3.14)) to 2003-2006 (aOR 1.18 (95% CI 0.91-1. 49)) and was not significantly increased for birth cohorts 2007-2010 and 2011-2014. For ART twins versus spontaneously conceived twins, the relative odds of CP was not statistically significantly increased throughout the study period.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of the study was a shorter follow-up time and younger age at first CP diagnosis for ART children compared with spontaneously conceived children. However, analyses ensuring a minimum of bias from differences in age at CP diagnosis and follow-up time confirmed the results, hence, we do not consider this to cause substantial bias.

WIDER IMPLICATIONS OF THE FINDINGS

A SET policy in ART treatments has the potential to reduce the increased risk of cerebral palsy in the ART population due to lower rates of multiple deliveries. At a time with high survival rates of frozen/thawed embryos, this study provides a strong argument against the continued use of multiple embryo transfer in most ART settings. Larger cohort studies including also the number of gestational sacs in early pregnancy will be preferable to show an effect of vanishing twins on the risk of CP in the ART population.

STUDY FUNDING/COMPETING INTEREST(S)

The study was financed by grants from NordForsk (grant number 71450), Elsass Foundation (19-3-0444), the ALF-agreement (ALFGBG 70940), and The Research Fund of Rigshospitalet, Copenhagen University Hospital. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

ISRCTN11780826.

Cerebral palsy in children born after assisted reproductive technology: a meta-analysis

BACKGROUND

Several studies have assessed the association between cerebral palsy (CP) and assisted reproductive technology (ART), but the results remain controversial. We conducted a meta-analysis to evaluate the risk of CP after ART compared with natural conceptions and to examine CP risk separately in ART singletons, multiples and preterm births.

METHODS

Web-based databases (PubMed, Embase, the Cochrane Library, and Web of Science) were searched until November 22, 2020. Studies which compare CP rates after ART with natural conceptions were included. The Newcastle-Ottawa Scale was used to assess the quality of the included studies. Effect estimates were extracted and combined using the fixed-effects or random-effects model depending on the heterogeneity test.

RESULTS

There were nine studies included in the meta-analysis. The included studies were of moderate or high quality. A significantly higher risk of CP [odds ratio (OR) = 2.17, 95% confidence interval (CI) 1.72-2.74] was found in ART children (n = 89,214) compared with naturally conceived children (n = 4,160,745). The significantly higher risk decreased when data were restricted to singletons (OR = 1.36, 95% CI 1.16-1.59) and disappeared when data were restricted to multiples (OR = 1.05, 95% CI 0.86-1.29) or preterm births (OR = 1.53, 95% CI 0.66-3.56). Subgroup and sensitivity analyses indicated that the overall results were robust.

CONCLUSIONS

The risk of CP is increased more than two-fold after ART. This increased risk is largely due to increased rates of multiple birth and preterm delivery in ART children.

Prediction of oocyte quality using mRNA transcripts screened by RNA sequencing of human granulosa cells

RESEARCH QUESTION

Can RNA transcripts of granulosa cells be used to assess oocyte quality? The possibility of predicting the developmental competence of oocytes by RNA sequencing analysis of granulosa cells was evaluated.

DESIGN

Granulosa cell samples were collected from 29 women undergoing assisted reproductive technology treatment and divided into two groups: 14 samples from the high blastocyst rate group and 15 from the low blastocyst rate group. Ten samples from each group were selected for RNA sequencing.

RESULTS

A total of 129 differentially expressed genes associated with high developmental competence of oocytes were identified. COL1A2, renin and COL1A1 were selected and further examined by quantitative real-time polymerase chain reaction (qRT-PCR). Expression levels of COL1A2 and renin by qRT-PCR were consistent with the results of RNA sequencing.

CONCLUSION

RNA sequencing data could provide novel marker genes for the non-invasive evaluation of oocyte quality and embryo developmental competence.

Associations of IVF singleton birthweight and gestation with clinical treatment and laboratory factors: a multicentre cohort study

STUDY QUESTION

Do IVF treatment and laboratory factors affect singleton birthweight (BW)?

SUMMARY ANSWER

BWs of IVF-conceived singleton babies are increasing with time, but we cannot identify the specific treatment factors responsible.

WHAT IS KNOWN ALREADY

IVF-conceived singleton babies from fresh transfers have slightly lower BW than those conceived naturally, whilst those from frozen embryo transfer (FET) cycles are heavier and comparable to naturally conceived offspring. Our recent studies have shown that BW varies significantly between different IVF centres, and in a single centre, is also increasing with time, without a corresponding change in BWs of naturally conceived infants. Although it is likely that factors in the IVF treatment cycle, such as hormonal stimulation or embryo laboratory culture conditions, are associated with BW differences, our previous study designs were not able to confirm this.

STUDY DESIGN, SIZE, DURATION

Data relating to BW outcomes, IVF treatment and laboratory parameters were collated from pre-existing electronic records in five participating centres for all singleton babies conceived between August 2007 and December 2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Seven thousand, five hundred and eighty-eight births, 6207 from fresh and 1381 from FET. Infants with severe congenital abnormalities were excluded. The primary outcome of gestation-adjusted BW and secondary outcomes of unadjusted BW and gestation were analysed using multivariable regression models with robust standard errors to allow for the correlation between infants with the same mother. The models tested treatment factors allowing for confounding by centre, time and patient characteristics. A similar matched analysis of a subgroup of 379 sibling pairs was also performed.

MAIN RESULTS AND THE ROLE OF CHANCE

No significant associations of birth outcomes with IVF embryo culture parameters were seen independent of clinic or time, including embryo culture medium, incubator type or oxygen level, although small differences cannot be ruled out. We did not detect any significant differences associated with hormonal stimulation in fresh cycles or hormonal synchronization in FET cycles. Gestation-adjusted BW increased by 13.4 (95% CI 0.6-26.1) g per year over the period of the study, and babies born following FET were 92 (95% CI 57-128) g heavier on average than those from the fresh transfer.

LIMITATIONS, REASONS FOR CAUTION

Although no specific relationships have been identified independent of clinic and time, the confidence intervals remain large and do not exclude clinically relevant effect sizes. As this is an observational study, residual confounding may still be present.

WIDER IMPLICATIONS OF THE FINDINGS

This study demonstrates the potential for large scale analysis of routine data to address critical questions concerning the long-term implications of IVF treatment, in accordance with the Developmental Origins of Health and Disease hypothesis. However, much larger studies, at a national scale with sufficiently detailed data, are required to identify the treatment parameters associated with differences in BW or other relevant outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the EU FP7 project grant, EpiHealthNet (FP7-PEOPLE-2012-ITN-317146). No competing interests were identified.

TRIAL REGISTRATION NUMBER

N/A.

The late vanishing of a co-twin contributes to adverse perinatal outcomes in the surviving singleton

STUDY QUESTION

Is the vanishing of a co-twin after or before the ultrasonic registration of cardiac activity at approximately 6-8 weeks of gestation associated with adverse perinatal outcomes?

SUMMARY ANSWER

The timing of the demise of a co-twin after the registration of cardiac activity is an independent risk factor for adverse perinatal outcomes.

WHAT IS KNOWN ALREADY

A significant body of evidence has confirmed that vanishing twin (VT) pregnancies are associated with higher levels of risk for preterm birth (PTB), low birthweight (LBW), small-for-gestational age (SGA) and perinatal mortality, compared with singleton pregnancy. However, the impact of co-twin vanishing, before or after the presence, of cardiac activity, on perinatal outcomes has yet to be extensively investigated.

STUDY DESIGN, SIZE, DURATION

We retrospectively reviewed the medical records of 38 876 singletons delivered from ART cycles between 2006 and 2018, at the Peking University Third Hospital.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 35 188 singletons were delivered from the singleton pregnancy group, 2256 singletons from the VT pregnancy group after that cardiac activity was noted, and 1432 singletons were delivered from the VT pregnancy group before cardiac activity could be registered. Using the Poisson model, the adjusted risk ratio (aRR) was used to estimate the incidence of PTB, LBW, SGA and perinatal mortality, in the pregnancies of two types of VT compared with singleton pregnancies after correction for potential confounding factors.

MAIN RESULTS AND THE ROLE OF CHANCE

The vanishing of a co-twin after the registration of cardiac activity was associated with an increased risk of perinatal mortality when compared with the group of singleton pregnancies (0.5% vs 0.2%; P = 0.006); this association still existed after adjustment for potential confounders (aRR 2.19, 95% CI 1.12-4.30; P = 0.023). Furthermore, it was significantly associated with a higher risk of PTB (all cycles aRR 2.00, 95% CI 1.77-2.24; P < 0.001; fresh transfer aRR 2.06, 95% CI 1.78-2.38; P < 0.001; frozen transfer aRR 1.87, 95% CI 1.52-2.28; P < 0.001), LBW (all cycles aRR 2.47, 95% CI 2.12-2.88; P < 0.001; fresh transfer aRR 2.50, 95% CI 2.07-3.02; P < 0.001; frozen transfer aRR 2.39; 95% CI 1.83-3.12; P < 0.001) and SGA (all cycles aRR 1.56, 95% CI 1.35-1.80; P < 0.001; fresh transfer aRR 1.53, 95% CI 1.29-1.81; P < 0.001; frozen transfer aRR 1.62, 95% CI 1.24-2.11; P < 0.001). However, prior to the presence of cardiac activity, the vanishing of a co-twin was not associated with a higher risk of perinatal mortality (all cycles aRR 0.71, 95% CI 0.17-2.92; P = 0.636; fresh cycles aRR 0.51, 95% CI 0.07-3.70; P = 0.502; frozen cycles aRR 1.29, 95% CI 0.17-9.66; P = 0.803), PTB (all cycles aRR 1.11, 95% CI 0.91-1.34; P = 0.301; fresh cycles aRR 1.10, 95% CI 0.87-1.39; P = 0.447; frozen cycles aRR 1.13, 95% CI 0.81-1.58; P = 0.467), LBW (all cycles aRR 1.19, 95% CI 0.91-1.55; P = 0.207; fresh cycles aRR 1.08, 95% CI 0.77-1.51; P = 0.668; frozen cycles aRR 1.45, 95% CI 0.93-2.25; P = 0.100) and SGA (all cycles aRR 1.09, 95% CI 0.89-1.35; P = 0.405; fresh cycles aRR 0.97, 95% CI 0.75-1.26; P = 0.839). Pregnancies involving the two types of VT were significantly different in terms of PTB (all cycles aRR 1.80, 95% CI 1.45-2.24; P < 0.001; fresh cycles aRR 1.88, 95% CI 1.44-2.45; P < 0.001; frozen cycles aRR 1.65, 95% CI 1.13-2.40; P = 0.009), LBW (all cycles aRR 2.08, 95% CI 1.55-2.79; P < 0.001; fresh cycles aRR 2.32, 95% CI 1.61-3.36; P < 0.001; frozen cycles aRR 1.65, 95% CI 1.01-2.70; P = 0.046) and SGA (all cycles aRR 1.70, 95% CI 1.36-2.11; P < 0.001; fresh cycles aRR 1.87, 95% CI 1.42-2.45; P < 0.001).

LIMITATIONS, REASONS FOR CAUTION

The present data are not able to differentiate between co-twin demise occurring in the first or second trimester. Because the second trimester ultrasound scan is not an integral aspect of IVF assessment, this information was not available in the database.

WIDER IMPLICATIONS OF THE FINDINGS

Adverse perinatal outcomes in ART babies can be avoided by replacing one embryo at a time. It is possible to apply selective single embryo transfer strategy for all while maintaining acceptable success rates.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Natural Science Foundation of China for Young Scholars (Reference number: 31801251). No competing interests to declare.

TRIAL REGISTRATION NUMBER

not applicable.

School performance in children born after ICSI

STUDY QUESTION

Do children conceived after ICSI have similar school performance as children born after IVF?

SUMMARY ANSWER

Children born after ICSI have similar school performance compared to children born after IVF.

WHAT IS KNOWN ALREADY

Studies concerning the cognitive skills of children born after ICSI have shown diverging results.

STUDY DESIGN, SIZE, DURATION

This nationwide, register-based cohort study included all singleton children born after ICSI (n = 6953), IVF (n = 11 713) or spontaneous conception (SC) (n = 2 022 995), in Sweden between 1985 and 2006.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Singleton children born after ICSI were identified in national IVF registers, cross-linked with the Medical Birth Register (MBR), the National Patient Register (NPR) and the Swedish Cause of Death Register (CDR) for characteristics and medical outcomes. Data on school performance, parental education and other parental characteristics were obtained through cross-linking to the National School Registry and to Statistics Sweden. The main control group, which consisted of children born after IVF, was identified in the national IVF registries while the second control group, consisting of children born after SC, was identified from the MBR. Simple and multivariable linear regression was used for analysis of continuous variables, and logistic regression was used for the analysis of binary outcomes. Adjustments were made for sex, year of birth, maternal smoking during pregnancy, parental age, parity, parental region of birth, parental level of education and frozen embryo transfer.

MAIN RESULTS AND THE ROLE OF CHANCE

In the adjusted analyses, there was no significant difference between ICSI and IVF children for total score (adjusted odds ratios (AORs) 1.03; 95% CI −0.22 to 2.28; P = 0.11), specific subjects, qualifying for secondary school (AOR 1.02; 95% CI 0.82–1.26; P = 0.87) or poor school performance (AOR 0.92; 95% CI 0.75−1.14; P = 0.47). In the third grade, children born after ICSI had a significantly lower chance of passing all of the subtests in Mathematics (AOR 0.89; 0.83–0.96; P = 0.002) and Swedish (AOR 0.92; 0.85–0.99; P = 0.02) compared to children born after SC. When cross-linking children with missing data on school performances (2.1% for ICSI, 2.0% for IVF and 2.3% for SC) with the Cerebral Palsy Follow-up Register (CPUP) for cerebral palsy, 2.7% of ICSI children, 5.7% of IVF children and 1.7% of SC children without registered education were found. When cross-linking children with missing data on school performances with the NPR for mental retardation, 29.9% of ICSI children, 32.6% of IVF children and 35.0% of SC children with missing data were registered under such a diagnosis.

LIMITATIONS, REASONS FOR CAUTION

The main limitation was that test scores were missing in a small percentage in both ICSI and IVF children. Although we were able to cross-link this subpopulation with the CPUP and the NPR, these diagnoses only partly explained the missing scores. Other limitations were unmeasured and unknown possible confounders, such as information about infertility diagnoses and indication for ICSI, were not available.

WIDER IMPLICATIONS OF THE FINDINGS

These findings are important to most countries where IVF and ICSI are used since there may be differences in choice of procedure. In recent years, there has been an increasing trend towards using ICSI not only for treatment of male infertility but also when the sperm quality is normal. Our results indicate that the school performance of children born after ICSI is reassuring.

STUDY FUNDING/COMPETING INTEREST(S)

Financial support was received through Sahlgrenska University Hospital (ALFGBG – 70 940), Hjalmar Svensson Research Foundation and Nordforsk, project number 71 450. None of the authors declare any conflict of interest.

TRIAL REGISTRATION NUMBER

N/A

Risk of stillbirth in singleton gestations following in vitro methods of conception: a systematic review and meta-analysis

BACKGROUND

In vitro methods of conception are associated with adverse perinatal outcomes. It is unclear if the risk of stillbirth is increased also.

OBJECTIVE

This systematic review and meta-analysis aimed to estimate the risk of stillbirth in singleton gestations following in vitro methods of conception compared to non-in vitro conceptions.

SEARCH STRATEGY

A comprehensive search in PubMed, Embase, CINAHL, and Cochrane Library was undertaken from database inception to February 2021, with backward citation tracking.

SELECTION CRITERIA

Eligible studies included randomized controlled trials, cohort studies, or case-control studies that assessed stillbirth following in vitro fertilisation and/or intracytoplasmic sperm injection in comparison to non-in vitro methods of conception, including spontaneous conceptions, intrauterine insemination, and ovarian stimulation.

DATA COLLECTION AND ANALYSIS

The Newcastle-Ottawa Scale was used to assess risk of bias. A summary odds ratio (OR) for stillbirth following in vitro methods of conception compared to non-in vitro methods was calculated using a random-effects model for meta-analysis.

MAIN RESULTS

Thirty-three cohort studies met inclusion criteria. There was an increased risk of stillbirth with in vitro methods: OR 1.41 (95% CI 1.20-1.65); however, the crude baseline risk of stillbirth was low (4.44/1000 total births). Subgroup analysis did not demonstrate an increased risk when in vitro methods were compared to conception without in vitro methods in the context of subfertility.

CONCLUSIONS

Compared to non-in vitro conceptions, in vitro conceptions have an increased risk of stillbirth. However, there is insufficient evidence to demonstrate whether this risk is associated with in vitro techniques or underlying subfertility.

TWEETABLE ABSTRACT

This meta-analysis found an increased risk of stillbirth in singletons from in vitro methods of conception.

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.

Associations between first-trimester intrauterine hematoma and twin pregnancy outcomes: a retrospective cohort study

Background

In recent years, first-trimester intrauterine hematoma (IUH) has become increasingly common in twin pregnancy. The majority of studies on IUH have excluded twin pregnancies, and others did not differentiate between singleton and twin pregnancies. The impact of IUH on twin pregnancy is unclear. Therefore, the primary objective of our study was to examine associations between first-trimester IUH and pregnancy outcomes in twin pregnancies.

Methods

The data of 1020 twin pregnancies in women who received a routine examination from January 2014 to December 2018 were reviewed. We compared baseline data and pregnancy outcomes between those with and without IUH. Multivariable logistic regression analysis was used to adjust for possible confounding factors.

Results

A total of 209 patients (21.3%) developed IUH in the first trimester. First-trimester IUH was significantly associated with increased odds of miscarriage (adjusted odds ratio 14.27, 95% CI 8.25–24.70) and vanishing twin syndrome (adjusted odds ratio 3.26, 95% CI 1.11–4.61). However, there were no differences in the rates of stillbirth, preeclampsia, preterm labor (< 34 weeks), low birth weight, postpartum hemorrhage or fetal distress between the two groups. Maternal age, previous preterm birth, chorionicity in twins and the gestational week at first ultrasound did not differ between the two groups. The women with IUH had high rates of previous miscarriage (46.73% vs 38.37%, p = 0.01), assisted conception (48.56% vs 32.60%, p < 0.001) and accompanied vaginal bleeding (67.46% vs 13.43%, p < 0.001). According to the logistic regression analyses, these characteristics were not associated with pregnancy loss or vanishing twin syndrome. No IUH characteristics, including volume, largest diameter, or the presence of vaginal bleeding, were associated with pregnancy loss or vanishing twin syndrome before 20 weeks of gestation (P > 0.05).

Conclusion

In women with twin pregnancy, the presence of IUH in the first trimester was associated with the loss of one or both fetuses before 20 weeks of gestation. However, previous miscarriage, the conception method, the IUH size and the presence of vaginal bleeding were not independently associated with miscarriage or vanishing twin syndrome.

[Influence of twin pregnancy by assisted reproductive technology on neonatal outcomes]

OBJECTIVE

To study the influence of twin pregnancy by assisted reproductive technology (ART) versus twin pregnancy by spontaneous conception (SC) on neonatal outcomes.

METHODS

A retrospective analysis was performed for the clinical data of 3 356 live twins with a gestational age of ≥24 weeks who were born in Nanjing Maternal and Child Health Hospital from 2017 to 2019, with 2 006 twins (1 003 pairs) in the ART group and 1 350 (675 pairs) in the SC group. The two groups were compared in terms of the mother's general information and pregnancy comorbidities and the general information, diseases, and outcomes of neonates.

RESULTS

Compared with the SC group, the ART group had a significantly higher maternal age (P < 0.05) and significantly higher rates of primiparity, cesarean section, and cervical cerclage (P < 0.05). Compared with the SC group, the ART group had significantly higher incidence rates of maternal pregnancy comorbidities including hypertension, gestational diabetes, and postpartum hemorrhage (P < 0.05). Compared with the SC group, the ART group had a significantly lower mean gestational age of neonates (P < 0.05) and a significantly higher proportion of very-low-birth-weight infants (6.8% vs 5.8%, P < 0.05), while ART did not increase the risks of preterm birth and low Apgar score. There were no significant differences between the two groups in the mortality rate of neonates and the incidence rates of neonatal diseases including respiratory distress syndrome, stage II/III necrotizing enterocolitis, bronchopulmonary dysplasia, and grade III-IV intracranial hemorrhage (P > 0.05).

CONCLUSIONS

Compared with twin pregnancy by SC, twin pregnancy by ART does not increase the neonatal mortality rate and risk of adverse outcomes.

Vanishing Twins Conceived Through Fresh In Vitro Fertilization: Obstetric Outcomes and Placental Pathology

OBJECTIVE

To characterize the obstetric outcomes and placental pathology in live births arising from vanishing twin pregnancies compared with nonreduced in vitro fertilization (IVF) pregnancies.

METHODS

This is a retrospective cohort study of live births resulting from fresh embryo transfers after IVF cycles with autologous oocytes from 2004 through 2017 at a large academic fertility center. Clinical information and pathology reports were reviewed. Placental diagnoses were coded using established nosology by expert placental pathologists. Analysis of variance, Kruskal-Wallis, Pearson's χ, and Fisher exact tests were used, as appropriate, to compare pathology categories between pregnancy outcomes. Mixed effects logistic regression models were generated to reveal the association between pregnancy outcome and placenta pathology, controlling for pregnancies arising in the same woman and various suspected confounders.

RESULTS

Of 905 fresh autologous IVF cycles with placental pathology available for review, we identified 73 vanishing twin pregnancies (8.1%), 556 singleton pregnancies (61.4%), and 276 twin pregnancies (30.5%). Vanishing twin syndrome was not associated with preterm delivery, route of delivery, growth restriction or other obstetric outcomes as compared with IVF singleton pregnancies. However, vanishing twin syndrome pregnancies showed distinctive placental pathologies including an increased rate of small placentas (less than the 10th percentile by weight), with more anatomical abnormalities than IVF singleton pregnancies (odds ratio 1.73, 95% CI 0.94-3.19; adjusted odds ratio 2.15, 95% CI 1.08-4.28). The frequency of placental vascular and inflammatory pathologies associated with IVF vanishing twin syndrome pregnancies were similar to that of IVF singleton pregnancies. Loss of a twin after 8 weeks of gestation was not associated with greater risks of placental pathologies.

CONCLUSION

In vitro fertilization pregnancies affected by vanishing twin syndrome did not have significant differences in obstetric or perinatal outcomes as compared with twin or singleton gestations. However, early twin loss was potentially associated with differences in placental development associated with a higher rate of small placentas and other anatomic pathologies.

Early and late pregnancy loss in women with polycystic ovary syndrome undergoing IVF/ICSI treatment: a retrospective cohort analysis of 21 820 pregnancies

OBJECTIVE

To examine early and late pregnancy loss in women with and without polycystic ovary syndrome (PCOS) undergoing IVF/ICSI transfers.

DESIGN

Retrospective cohort study.

SETTING

Reproductive medicine centre at a tertiary hospital.

POPULATION

We studied women with a positive β-human chorionic gonadotropin (β-hCG) after in vitro fertilisation/intra-cytoplasmic sperm injection (IVF/ICSI) treatment from May 2014 to April 2019.

METHODS

Odds ratios (OR) for early (≤13 weeks) and late (>13 weeks) pregnancy loss were calculated among women with and without PCOS for plurality of the pregnancy with adjustment for confounding factors.

MAIN OUTCOME MEASURES

Early pregnancy loss (EPL) and late pregnancy loss (LPL).

RESULTS

From 21 820 women identified with a positive β-hCG, 2357 (10.8%) women had PCOS, and 19 463 (89.2%) women did not. EPL occurred in 16.6% (391) of women with PCOS versus 18.3% (3565) in women with non-PCOS (OR 0.89, 95% CI 0.79-0.99, P = 0.04). After adjustment for age and other confounders, the rate of EPL was not statistically significantly associated with PCOS status (adjusted OR [aOR] 0.91, 95% CI 0.80-1.05). Women with PCOS demonstrated a higher rate of LPL (6.4% in PCOS versus 3.6% in non-PCOS, OR 1.81, 95% CI 1.48-2.21, P < 0.001). In multivariable analysis, the potential impact of PCOS was less strong (aOR 1.38, 95% CI 0.96-1.98), with BMI and maternal comorbidities also associated with LPL (aOR 1.08, 95% CI 1.04-1.1 and aOR 2.07, 95% CI 1.43-3.00, respectively).

CONCLUSIONS

Polycystic ovary syndrome was not independently associated with EPL. There was an increased risk of LPL but this difference was not statistically significant.

TWEETABLE ABSTRACT

Polycystic ovary syndrome women are at increased risk of late pregnancy loss, partly driven by elevated BMI and maternal comorbidities.

Early Serum hCG in IVF: Are We Trending in the Right Direction?

Human chorionic gonadotropin (hCG) measurements may be the earliest indicator of fertility cycle success, available several weeks before an ultrasound would be diagnostic for pregnancy. Outcomes of these cycles are high stakes for a couple, and the earliest reassurance of a normal pregnancy would be beneficial for their well-being. Additionally, earlier diagnosis can allow for more rapid management by providers in the case of abnormal pregnancies. Therefore, establishing normal values for initial hCG level and early hCG kinetics is of great interest. There are many factors involved in assisted reproductive techniques that may lead to alterations in hCG kinetics when compared with spontaneous pregnancies. We aim to characterize normal hCG values for in vitro fertilization (IVF) pregnancies and review how different aspects of the IVF process may alter these trends in order to establish how best to counsel patients during the waiting period.

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.

Is vanishing twin syndrome associated with adverse obstetric outcomes of ART singletons? A systematic review and meta-analysis

PURPOSE

The objective of our meta-analysis was to estimate the effect of VTS on obstetric outcomes of ART singletons.

METHODS

PubMed, Embase, MEDLINE, and ClinicalTrials.gov were searched up to January 2019 to find studies reporting the obstetric outcomes of ART singletons with VTS. Dichotomous data were expressed as odds ratios (OR) with 95% confidence intervals (CI). Continuous data were expressed as weighted mean difference (WMD) with 95% CI.

RESULTS

A total of 17 observational studies encompassing more than 60,000 ART singletons were included in this meta-analysis. The impact of VTS on singletons was highly dependent on the definition of VTS, precisely, the vanishing timing and intrauterine growth stage. When VTS happened at or before 14 weeks, regardless of intrauterine growth stage, there were no differences in terms of gestational age (GA) [WMD = - 0.08, 95% CI = - 0.27, 0.10], preterm birth (< 37 weeks) (PTB) [OR = 1.23, 95% CI = 0.89, 1.70], and low birth weight (< 2.5 kg) (LBW) [OR = 1.56, 95% CI = 1.00, 2.43] in original singletons versus singleton with VTS. On the contrary, VTS occurred after 14 weeks was associated with significantly shorter GW and lower BW, as well as higher risks of PTB and LBW. When the sac reduced in VTS was an empty gestational sac, there would be no differences in GW, PTB, and LBW between singletons versus singletons with VTS, whereas the loss of a fetus with cardiac-activity was associated with adverse obstetric outcomes.

CONCLUSIONS

This meta-analysis suggests whether or not VTS is harmful to obstetric outcomes is highly dependent on the vanishing timing and intrauterine growth stage.

Should vanishing twin pregnancies be systematically excluded from cell-free fetal DNA testing?

OBJECTIVE

To demonstrate the feasibility of cell-free DNA (cfDNA) testing in vanishing twin (VT) pregnancies in routine clinical practice.

METHODS

Our study included 24 874 singleton and 206 VT consecutive pregnancies. Cell-free DNA was analyzed by massively parallel sequencing. Both aneuploidy analysis (chromosomes 13,18, 21, X, and Y) and fetal fraction estimation were performed according to an Illumina algorithm. Contaminant DNA contribution from the demised co-twin was studied in detail.

RESULTS

VT pregnancies exhibited a higher prevalence of screen-positive cases (5.8% vs 2.5%), sex discrepancies (10.2% vs 0.05%), and false positive rates (FPR) (2.6% vs 0.3%) than singleton pregnancies. However, their incidence was significantly lower in tests performed after the 14th week (screen-positive cases: 3.1%; sex discrepancies: 7.8%; and FPR: 0.8%). Among the 12 cases in which cfDNA was performed at two time points, fading of contaminating cfDNA was observed in four cases with a sex discrepancy and in one false positive for trisomy 18, resulting in a final correct result.

CONCLUSIONS

Our data suggest VT pregnancies could be included in cfDNA testing as long as it is applied after the 14th week of pregnancy. However, future studies to validate our findings are needed before including VT cases in routine clinical practice. Once established, unnecessary invasive procedures could be avoided, mitigating negative emotional impact on future mothers.

Comparison of the rates of preterm birth and low birth weight of vanishing twin and primary pregnancies conceived with assisted reproductive technology

OBJECTIVES

The purpose of this study was to compare the rate of preterm birth, low birth weight, and foetal growth restriction in assisted reproductive technology (ART) singleton pregnancies diagnosed with vanishing twin (VT) syndrome to those of ART pregnancies that were originally singleton pregnancies.

METHODS

In this retrospective study, 177 pregnancies diagnosed with VT syndrome were matched and compared with 218 primary singleton pregnancies. The preterm birth and low birth weight rates of these two groups were evaluated. All pregnancies were conceived through ART and delivered at Peking University First Hospital and Hebei Xingtai Infertility Hospital from 2014 to 2016.

RESULTS

The preterm delivery rate (20.90 vs. 8.72%, p<0.05) was significantly higher in the ART singletons with VT syndrome than in the control singleton group. The proportion of low-birth-weight (<2500 g) infants was also higher in the VT group than in the primary singleton group (10.73 vs. 3.67%, p<0.05). In addition, the preterm birth rate of the naturally conceived singletons was significantly lower than that of the ART singletons (6.00 vs. 14.18%, p<0.05).

CONCLUSIONS

ART singleton pregnancies with VT syndrome have higher rates of preterm birth and low-birth-weight new-borns than ART pregnancies that were originally singleton pregnancies.

The impact of IVF on birthweight from 1991 to 2015: a cross-sectional study

STUDY QUESTION

Has birthweight (BW) changed over time among IVF-conceived singletons?

SUMMARY ANSWER

Singleton BW has increased markedly over the past 25 years.

WHAT IS KNOWN ALREADY

IVF conceived singletons have had a higher incidence of low BW compared to spontaneously conceived singletons, and this has raised concerns over long-term increased risks of cardio-metabolic disease. However, few causal links between IVF procedures and BW have been robustly established, and few studies have examined whether BW has changed over time as IVF techniques have developed.

STUDY DESIGN, SIZE, DURATION

A total of 2780 live born singletons conceived via IVF or ICSI treated in the reproductive medicine department of a single publicly funded tertiary care centre between 1991 and 2015 were included in this retrospective study. The primary outcome measure was singleton BW adjusted for gestational age, maternal parity and child gender. Multivariable linear regression models were used to estimate the associations between patient prognostic factors and IVF treatment procedures with adjusted BW.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All singletons conceived at the centre following IVF/ICSI using the mother's own oocytes, and non-donated fresh or frozen/thawed embryos with complete electronic data records, were investigated. Available electronic records were retrieved from the Human Fertilization and Embryology Authority for dataset collation. Multiple linear regression analysis was used to evaluate associations between IVF treatment parameters and BW, after adjusting for the year of treatment and patient characteristics and pregnancy factors.

MAIN RESULTS AND THE ROLE OF CHANCE

In the primary multivariable model, singleton BW increased by 7.4 g per year (95% CI: 3.2-11.6 g, P = 0.001), an increase of close to 180 g throughout the 25-year period after accounting for gestational age, maternal parity, child gender, IVF treatment parameters, patient prognostic characteristics and pregnancy factors. Fresh and frozen embryo transfer-conceived singletons showed a similar increase in BW. Frozen/thawed embryo transfer conceived singletons were on average 53 g heavier than their fresh embryo conceived counterparts (95% CI: 3.7-103.3 g, P = 0.035).

LIMITATIONS, REASONS FOR CAUTION

The independent variables included in the study were limited to those that have been consistently recorded and stored electronically over the past two decades.

WIDER IMPLICATIONS OF THE FINDINGS

There has been a progressive BW increase in IVF singletons over time in one large centre with consistent treatment eligibility criteria. Such a change is not seen in the general population of live born singletons in the UK or other developed countries, and seems to be specific to this IVF population. This may be a reflection of changes in practice such as undisturbed extended embryo culture to the blastocyst stage, optimized commercial culture media composition, single embryo transfer and ICSI. Moreover, singletons conceived from frozen/thawed embryos had higher birth weights when compared to their fresh embryo transfer counterparts. The causal pathway is unknown; however, it could be due to the impact on embryos of the freeze/thaw process, self-selection of embryos from couples who produce a surplus of embryos, and/or embryo replacement into a more receptive maternal environment.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the EU FP7 project grant, EpiHealthNet (FP7-PEOPLE-2012-ITN-317146). The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

The risk of preterm birth in vanishing twin: A multicenter prospective cohort study

Objective

To evaluate not only the risk of total preterm birth (PTB) but also spontaneous preterm birth (sPTB) and indicated preterm birth (iPTB) in vanishing twin (VT).

Study design

This is a secondary analysis of a multicenter prospective cohort study. In 12 different healthcare institutions, women with singleton pregnancies were enrolled in early pregnancy and followed up till delivery.

Results

A total of 4,746 women were included in the final analysis, and. the frequency of VT was 1.1% (54/4746). VT group had a higher risk for total PTB (PTB<34 weeks, 2.1% vs. 14.8%, p<0.001; PTB<32 weeks, 1.6% vs. 13.0%, p<0.001; PTB<28 weeks, 0.9% vs. 13.0%, p<0.001) than singleton group. The VT group had increased risk for both sPTB and iPTB (<34 weeks, <32 weeks, and <28 weeks), and this increased risk for sPTB and iPTB in VT group remained significant even after controlling for confounders such as maternal age, parity, pre-pregnancy BMI, and mode of conception.

Conclusion

Vanishing twin can be an independent risk factor for both sPTB and iPTB when compared with singleton pregnancy.

Association between endometrial thickness and neonatal outcomes in intrauterine insemination cycles: a retrospective analysis of 1,016 live-born singletons

BACKGROUND

Decreased endometrial thickness (EMT) has been suggested to be associated with reduced birthweight of in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) newborns. Considering the differences in ovarian stimulation degree and laboratory procedures between IVF/ICSI and IUI treatment, we aim to investigate whether EMT has any influence on IUI infant outcomes as well.

METHODS

This was a retrospective cohort study of 1016 patients who had singleton livebirths after IUI treatment cycles from January 2008 to December 2018 at a tertiary-care academic medical center in China. Patients were categorized into three groups by the 10th and 90th percentile of peak EMT: ≤7.6, 7.7-13.0 and ≥ 13.1 mm. The primary outcomes of the study were preterm birth (PTB), low birthweight (LBW) and small-for-gestational age (SGA). Multiple regression analyses were performed after controlling for a variety of potential confounders.

RESULTS

No significant differences were found among the three groups in gestational age, birthweight and birthweight Z-score. Compared with the EMT 7.7-13.0 mm group, the incidences of PTB, LBW and SGA were 5.5% (adjusted odds ratio [aOR] 0.81, 95% confidence interval [CI] 0.33-2.01), 6.4% (aOR 1.44, 95% CI 0.58-3.58) and 7.3% (aOR 1.21, 95% CI 0.53-2.76) in the EMT ≤7.6 mm group, respectively. Similarly, EMT ≥13.1 mm was not significantly associated with risks of PTB (aOR 0.63, 95% CI 0.24-1.65), LBW (aOR 0.57, 95% CI 0.17-1.95) and SGA (aOR 0.73, 95% CI 0.28-1.92). The odds of other adverse neonatal outcomes, including macrosomia, large-for-gestational age and major congenital malformations, did not show significant differences before and after adjustment in both EMT ≤7.6 and ≥ 13.1 mm groups.

CONCLUSIONS

EMT is not independently associated with adverse perinatal outcomes in IUI cycles. This novel finding would provide reassuring information for IUI patients with thin endometrial linings regarding their neonatal health. However, further prospective cohort studies with larger datasets are needed to confirm the conclusion.

Associated perinatal determinants of vanishing twin pregnancies achieved by in vitro fertilization vs. spontaneous conception

PURPOSE

To evaluate whether vanishing twin (VT) pregnancies following spontaneous conception have a more adverse perinatal outcome than those conceived after assisted reproduction techniques.

METHODS

The retrospective cohort study consisted of 316 VT pregnancies derived from a hospital database between January 1994 and January 2016 (81 after IVF/ICSI and 235 after spontaneous conception).

RESULTS

VT was significantly more prevalent after spontaneous conception (in 22.0% of twins) than after IVF/ICSI (in 14.5% of twins). VT pregnancies were significantly more associated with pre-gestational and gestational diabetes mellitus (GDM) in IVF/ICSI pregnancies compared to those spontaneously conceived [adjusted odds ratio (AOR): 4.12 and 11.1, respectively]. IVF-related placental insertion abnormalities were significantly higher in VT pregnancies. A high risk for VT was recorded in the spontaneous group for those who had previously undergone an induced abortion (AOR 0.56) or second-trimester fetal loss (AOR 0.67). The VT phenomenon was a major prognosticator of intrauterine growth retardation (IUGR) for the remaining fetus in IVF pregnancies (AOR 5.12). After controlling for covariates conjointly, advanced age (AOR 1.3), GDM (AOR 2.1), hypertensive disorders (AOR 3.5), primiparity (AOR 3.8), and placentation anomalies all represented independent risk factors for VT in IVF pregnancies.

CONCLUSIONS

IVF/ICSI poses a higher risk for an adverse perinatal outcome following VT pregnancies as compared with those spontaneously conceived.

Outcome of ICSI pregnancies with spontaneous loss of a co-twin compared with singleton ICSI pregnancies: Single center experience

AIM

To compare the outcome of intracytoplasmic sperm injection (ICSI) pregnancies complicated by spontaneous loss of a dichorionic co-twin with that of singleton ICSI pregnancies.

METHODS

The study group included dichorionic ICSI pregnancies with co-twin loss (n = 33) and the control group included ICSI pregnancies with a singleton from the beginning (n = 327). Primary outcome measures were obstetric complications, including preterm delivery, newborn small for gestational age, gestational diabetes, gestational hypertensive disorders and abruptio placenta; admission to neonatal intensive care unit (NICU) and perinatal mortality observed in the study and control groups. Statistical analysis was performed using spss for Windows, version 22.0.

RESULTS

In the study group, there were 26 cases of first trimester (early) and 7 cases of second or third trimester (late) co-twin losses. Mean gestational age at delivery and mean birth weight were significantly lower in the whole study group compared to control (P < 0.05). Preterm delivery and NICU admission rates were significantly higher in the whole study group, compared to control (39.3% vs 14.6% and 36.36% vs 11.69% respectively, P < 0.05), but did not show significant difference between early loss subgroup and control (P > 0.05). Preterm delivery rate was significantly higher in the late loss subgroup compared to the early loss subgroup (85.71% vs 26.92% P < 0.05).

CONCLUSION

Loss of a co-twin in dichorionic ICSI pregnancies is associated with increased risk of preterm birth. This risk is significantly higher in cases with late loss compared to the early loss cases.

Birthweight of IVF children is still a current issue and still related to maternal factors

RESEARCH QUESTION

Does fresh embryo transfer after IVF with or without intracytoplasmic sperm injection (ICSI) increase the small for gestational age (SGA) rate, and frozen embryo transfer (FET) after IVF with or without ICSI increase the large for gestational age (LGA) rate versus natural conception?

DESIGN

Retrospective comparison of an exposed historical group/cohort involving singletons conceived after fresh embryo transfer and after FET with an unexposed group/cohort involving singletons conceived after a natural conception.

RESULTS

A total of 1961 fresh embryo transfer babies and 366 FET babies were compared with 6981 natural conception babies. The SGA rate in fresh embryo transfer babies was not significantly different to natural conception babies (6.9% versus 6.8%, P = 0.856). This outcome was not influenced by the fresh embryo transfer (adjusted odds ratio [aOR] 1.0; 95% confidence interval [CI] 0.8-1.3), but rather by a low rate of multiparity (aOR 0.5; 95% CI 0.3-0.7), advanced maternal age (aOR 1.1; 95% CI 1.0-1.2), maternal underweight (aOR 1.5; 95% CI 1.1-2.1), maternal smoking or cessation during pregnancy (aOR 1.8; 95% CI 1.4-2.3), pre-existing hypertension (aOR 2.3; 95% CI 1.3-4.1) and pregnancy-induced hypertension (aOR 2.5; 95% CI 1.7-3.7). The LGA rate in FET babies was significantly different from natural conception babies (6.6% versus 3.2%, P = 0.012). This outcome was influenced by the transfer of frozen embryos (aOR 2.2; 95% CI 1.3-3.8) and by a high maternal weight (aOR 1.9; 95% CI 1.1-3.6).

CONCLUSIONS

Maternal background and obstetric parameters are more likely to influence the SGA rate than fresh embryo transfer conception. FET conception could be associated with an increase in LGA rate.

Perinatal and Peripartum Outcomes in Vanishing Twin Pregnancies Achieved by In Vitro Fertilization

OBJECTIVE

To compare perinatal and peripartum outcomes of vanishing twin gestations with singleton and dichorionic twin gestations in pregnancies conceived by in vitro fertilization.

METHODS

We conducted a retrospective cohort study of vanishing twin pregnancies after fresh and cryopreserved autologous in vitro fertilization cycles performed at our institution from 2007 to 2015. Singleton, dichorionic twin, and dichorionic twin pregnancies with spontaneous reduction to one by 14 weeks of gestation (vanishing twins) were included. Analysis was restricted to patients with a live birth delivery at our institution at or beyond 24 weeks of gestation. The primary outcomes were gestational age and birth weight at delivery; secondary outcomes included peripartum morbidities. A subanalysis further differentiated the vanishing twin pregnancies between those in which demise of the twin occurred before compared with after identification of fetal cardiac activity. Logistic regression models were used to estimate the adjusted odds ratio (OR) with a 95% CI of outcomes.

RESULTS

There were 1,189 pregnancies that met inclusion criteria (798 singleton, 291 twin, and 100 vanishing twin). The mean gestational age at birth and birth weights were 38.6±2.3 weeks of gestation and 3,207±644 g in singleton pregnancies, 35.5±2.7 weeks of gestation and 2,539±610 g in twin pregnancies, and 38.5±1.8 weeks of gestation and 3,175±599 g in vanishing twin pregnancies. When compared with twins, those with a vanishing twin had lower odds of preterm delivery (OR 0.13, 95% CI 0.07-0.23; adjusted OR 0.12, 95% CI 0.07-0.22) and small-for-gestational-age birth weight (OR 0.24, 95% CI 0.13-0.45; adjusted OR 0.14, 95% CI 0.07-0.28).

CONCLUSION

In pregnancies conceived by in vitro fertilization that progress to at least 24 weeks of gestation, vanishing twin and singleton pregnancies had similar perinatal and peripartum outcomes. Both were significantly better than twin pregnancies.

Perinatal outcomes of singleton live births with and without vanishing twin following transfer of multiple embryos: analysis of 113 784 singleton live births

STUDY QUESTION

Does transfer of multiple embryos affect perinatal outcomes of resulting singleton live births following ART?

SUMMARY ANSWER

There is a higher risk of preterm birth (PTB) and low birthweight (LBW) in singleton live births associated with spontaneous reduction of an initial multiple to singleton gestation following transfer of multiple embryos.

WHAT IS KNOWN ALREADY

Singleton pregnancies following ART are at a higher risk of adverse perinatal outcomes compared to spontaneous conceptions. Earlier studies have found an increased risk of PTB and LBW in singletons following transfer of multiple embryos versus single embryo transfer (SET). However, these studies did not address the specific role of vanishing twin, i.e. spontaneous reduction of an initial multiple to singleton gestation.

STUDY DESIGN, SIZE, DURATION

Anonymised data on all ART cycles performed in the UK were obtained from the Human Fertilization and Embryology Authority. Data from 1991 to 2011 involving 508 410 fresh and 131 157 frozen autologous ART cycles resulting in 95 779 and 18 005 singleton live births, respectively, were analyzed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Fresh and frozen ART cycles were analyzed separately to compare perinatal outcomes of PTB and LBW of singleton live births resulting from transfer of multiple (≥2) embryos versus SET. Logistic regression analysis was performed adjusting for confounders. Subgroup analyses were carried out for perinatal outcomes of singleton live births with initial multiple or initial single gestational sacs following transfer of multiple embryos versus singleton live births following SET.

MAIN RESULTS AND THE ROLE OF CHANCE

In fresh cycles, there was a significantly higher risk of PTB (adjusted odds ratio (aOR) 2.70, CI 2.37-3.05) and LBW (aOR 2.76, CI 2.44-3.13) in singleton live births with initial multiple gestational sacs but there was no significant difference in the risk of PTB (aOR 1.08, CI 1.00-1.16) or LBW (aOR 1.08, CI 1.00-1.16) in singleton live births with an initial single gestational sac following transfer of ≥2 embryos compared to those following SET. In frozen cycles, there was a significantly higher risk of PTB (aOR 2.13, CI: 1.55-2.93) and LBW (aOR 2.61, CI: 1.87-3.64) in singleton live births with initial multiple gestational sacs but there was no significant difference in the risk of PTB (aOR 1.02, CI: 0.88-1.18) or LBW (aOR 0.91, CI: 0.77-1.07) in the singleton live births with an initial single gestational sac following transfer of ≥2 embryos compared to those following SET.

LIMITATIONS, REASONS FOR CAUTION

While the analysis was adjusted for a number of known confounders, the dataset had no information for confounders such as smoking, BMI, previous obstetric history and comorbid medical conditions during pregnancy. The lack of information about the timing of occurrence of the vanishing phenomenon is another limitation because poorer perinatal outcomes of a surviving twin have been reported following second trimester fetal demise compared to the first trimester.

WIDER IMPLICATIONS OF THE FINDINGS

The study results suggest that the vanishing twin phenomenon is associated with increased risk of PTB and LBW in the resulting singleton live births and there was no increased risk when there was a single gestational sac from the outset following transfer of multiple embryos.

STUDY FUNDING/COMPETING INTERESTS

Nil.

Determinants of monozygotic twinning in ART: a systematic review and a meta-analysis

BACKGROUND

The incidence of monozygotic twins (MZT) after ART appears to be higher than the incidence after spontaneous conceptions contradicting the aim of ART to avoid multiple pregnancies because of the associated risks.

OBJECTIVE AND RATIONALE

The aim was to study the frequency of MZT after IVF and ICSI and how it is influenced by the day of embryo transfer, maternal age, zona pellucida manipulation, controlled ovarian stimulation, stimulation protocol, culture media and embryo quality.

SEARCH METHODS

Original studies and reviews were identified by searching the PubMed, Embase and Cochrane databases up to March 2017. The inclusion criterion was publications focusing on the five study questions related to MZT in our study. The exclusion criteria were articles that did not include blastocyst transfer, were on non-humans, were not published in peer-reviewed journals, and were based only on case studies. All of the articles were categorized according to the Oxford Centre for Evidence-based Medicine's 'Levels of Evidence', and quality and risk of bias assessment was performed with 'The Cochrane Collaboration's Risk of Bias Tools'. A meta-analysis was performed to study the impact of the day of embryo transfer on the MZT rate.

OUTCOMES

The literature search resulted in a total of 42 articles, including 38 original studies, for analysis. The included original studies reported a MZT rate with blastocyst transfer from zero to 13.2%. Our meta-analysis found a higher frequency of MZT after blastocyst transfer compared with cleavage-stage embryos transfer: odds ratio = 2.18, 95% CI: 1.93-2.48 (fixed effect meta-analysis). A younger maternal age may increase the MZT rate, and recent studies regarding the use of zona pellucida manipulating techniques have disagreed with the previous suspicion of a higher MZT rate after the use of these methods. The extended culture to-blastocyst stage is a potential risk factor for MZT, but it is uncertain whether this phenomenon is due to the extended time, culture media or greater likelihood of younger oocytes to reach the blastocyst stage. An increased frequency of MZT following the GnRH-agonist suppression protocol has been suggested, as well as a decreased frequency of MZT with high gonadotrophin doses, which could reflect an age-related effect. Only limited literature has focused on the role of embryo morphology in the MZT rate, therefore, this issue remains unresolved.

WIDER IMPLICATIONS

We found blastocyst transfer to be a risk factor for MZT. Hence, the results of this meta-analysis may weaken the previously proposed view that greater experience with blastocyst transfer and improved culture media could decrease the high rate of MZT after blastocyst transfer. To minimize the rate of MZT and the associated complications, the mechanisms underlying blastocyst transfer and MZT pregnancy must be elucidated.

Comparison of Perinatal Outcomes of Singletons Following Vanishing Twin Phenomenon and Singletons with Initial Single Gestational Sac Conceived Following Assisted Reproductive Technology: A Retrospective Analysis

Aim:

The aim of the study was to compare the perinatal outcomes between singletons following vanishing twin phenomenon and singletons arising from initial single gestational sac following assisted reproductive technology (ART) treatment.

Setting and Design:

This was a retrospective cohort study.

Materials and Methods:

A retrospective cohort study included analysis of all singleton births following ART over a period of 7 years (January 2010 –December 2016). All women who underwent fresh or frozen embryo ART cycles were followed up. The study population included all singleton births following spontaneous reduction of one of the gestational sacs in dichorionic diamniotic twin pregnancies. The perinatal outcome of this group was compared with those of singletons arising from the initial single gestational sac.

Results:

A total of 521 singleton births were recorded during the study period. In the study group, 72 singleton births had spontaneous reduction of one of the gestational sacs (vanishing twin group) and the remaining 449 had an initial single gestational sac. The risk for low birth weight (LBW) (14/72, 19.4% vs. 96/449, 21.6%) and preterm birth (PTB) (17/72, 23.6% vs. 134/449, 29.8%) was not significantly different between those singletons who had spontaneous reduction from two gestational sacs to single sac compared to those with initial single sac. The miscarriage rate was significantly lower in vanishing twin group compared to control group (7/84, 8.3% vs. 157/622, 25.2%; P = 0.01). The subgroup analysis based on spontaneous reduction occurring before or after the appearance of the embryonic pole also showed similar risk of PTB (11/41, 26.8.% vs. 9/31, 29.0%) and LBW (7/41, 17.1% vs. 9/31, 29.0%).

Conclusion:

Perinatal outcomes in singleton live births following vanishing twin phenomenon are similar to those pregnancies with an initial single gestational sac following ART.

Comparison of different types of twin pregnancies in terms of obstetric and perinatal outcomes: association of vanished twins with methylenetetrahydrofolate reductase (MTHFR) polymorphism(s)

PURPOSE

Vanished twin (VT) has been associated with poor perinatal outcomes. Our research aimed to investigate the outcomes of pregnancies with vanished twin and its possible association with methylenetetrahydrofolate reductase (MTHFR) polymorphisms.

METHODS

This study consisted of 30 of 38 VT pregnancies (group 1, VT group), 109 singletons (group 2), 70 spontaneous twins (group 3), and 101 in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) twins (group 4).

RESULTS

Most patients in group 1 (28/30) were tested for MTHFR genes (C677T or A1298C polymorphisms). Eight of the 38 pregnancies with VT (21.1%) resulted in miscarriage. The prevalence of "2 or more pregnancy losses" in the "obstetric history" in group 1 was higher (23.3%) than those in the other groups (p = 0.007, χ² = 17.8). The allelic frequencies of MTHFR 677 and MTHFR 1298 in group 1 were 0.268 and 0.429, respectively (higher than those in healthy population). The median birthweights in groups 1, 2, 3, and 4 were 2940, 3200, 2300, and 2095 g, respectively. The prevalence of respiratory distress syndrome was significantly higher in the IVF/ICSI twin pregnancy group (p < 0.001, χ² = 21.2). Early pregnancy loss and the presence of "2 or more miscarriages" in the obstetric history of pregnancies with VT were more frequent.

CONCLUSION

The coincidence of VT and MTHFR polymorphisms might play an incidental or factual role in this connection.

Do the children born after assisted reproductive technology have an increased risk of birth defects? A systematic review and meta-analysis

Background: Assisted reproductive technologies (ARTs) have made great progress. However, whether tube baby born after ART were at an increased risk of birth defects is not clear.Objective: To assess whether the ART increases the risk of birth defects in children born after ART.Search strategy: Medline, Google Scholar, and the Cochrane Library were searched.Selection criteria: Clinical trials that evaluate the risk of birth defect in children born after in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) and natural conceptions (NC) were included. The primary outcome was the prevalence of birth defects.Data collection and analysis: The relative risk was used as the summary measure with random effects model. We assessed heterogeneity between studies using the I² index.Main results: Totally 46 studies were included. The pooled relative risk (RR) estimated suggested there was an increased risk of birth defects in ART compared with the NC group (RR: 1.40; 95% CI 1.31-1.49). Twenty and fifteen studies were included to compare the risk of birth defects between NC and IVF/ICSI, respectively. The results indicated that both IVF and ICSI increase the risk of birth defects (IVF: RR 1.25; 95% CI 1.12-1.40; ICSI: RR 1.29; 95% CI 1.14-1.45). When subgroup according to plurality, 22 studies assessed the risk of birth defects after ART or NC in singletons and 15 studies evaluated the risk of birth defects in twins. The pooled RRs were 1.41 (95% CI 1.30-1.52) and 1.18 (95% CI 0.98-1.42), respectively.Conclusions: Children born after ART were at an increased risk of birth defects compared with NC. There was no difference in birth defects risk between ART twins and NC twins.