Vanishing Twin Pregnancies Research Articles

Cell-free DNA test for fetal chromosomal abnormalities in multiple pregnancies.

This study aimed to report the screening performance of cell-free DNA (cfDNA) testing for chromosomal abnormalities in twins, triplets, and vanishing twin pregnancies. Data were obtained from pregnant women with a multiple pregnancy or a vanishing twin pregnancy at ≥10 weeks' gestation who requested self-financed cfDNA testing between May 2015 and December 2021. Those that had positive screening results had diagnostic confirmatory procedures after counseling and consent. The performance of screening of the cfDNA test was determined by calculating confirmation rate and combined false-positive rate (cFPR). Data from 292 women were included after exclusion of those lost to follow-up, with no-result on cfDNA testing, or had reductions. Of the 292 pregnancies, 10 (3.4%) were triplets, including no cases of trisomy 21 and trisomy 18; 249 (85.3%) were twins, including 3 cases of trisomy 21 and no cases of trisomy 18 and 13; and 33 (11.3%) were vanishing twins, including 3 cases of trisomy 21 and 1 case of trisomy 18. The median (IQR) maternal age was 34 years (31-37). For triplet pregnancies, the initial no-result rate was 10.3% (95% confidence interval [CI] 3.6-26.4), all with results after redraw. For twin pregnancies, the initial no-result rate was 12.9% (95% CI 9.6-17.0), and the no-result rate after redraw was 1.6% (95% CI 0.7-3.6). For vanishing twins, there were no cases with no-result. All triplets had low-risk cfDNA results. The confirmation rate for trisomy 21 was 100% with a FPR at 0% due to the small number of positive cases for twins. For vanishing twins, one high-risk case for trisomy 21 and the only high-risk case for trisomy 18 were confirmed with a cFPR of 8.3% (n = 2/24; 95% CI 2.3-25.9). cfDNA testing in twin pregnancies has sufficient screening performance for trisomy 21 but the number of affected cases for other conditions is limited to draw any meaningful conclusion. The use of cfDNA testing in triplet pregnancies and vanishing twins remains an area for further research.

989 Maternal and ultrasound characteristics associated with persistence of cell-free DNA from a vanishing twin pregnancy

989 Maternal and ultrasound characteristics associated with persistence of cell-free DNA from a vanishing twin pregnancy

Non-invasive prenatal testing (NIPT) in twin pregnancies affected by early single fetal demise: A systematic review of NIPT and vanishing twins.

The screening performance of non-invasive prenatal testing (NIPT) in vanishing twin (VT) pregnancies is relatively unknown. To close this knowledge gap, we conducted a systematic review of the available literature. Studies describing the test performance of NIPT for trisomy 21, 18, 13, sex chromosomes and additional findings in pregnancies with a VT were retrieved from a literature search with a publication date until October 4, 2022. The methodological quality of the studies was assessed with the quality assessment tool for diagnostic accuracy studies-2 (QUADAS-2). The screen positive rate of the pooled data and the pooled positive predictive value (PPV) were calculated using a random effects model. Seven studies, with cohort sizes ranging from 5 to 767, were included. The screen positive rate of the pooled data for trisomy 21 was 35/1592 (2.2%), with a PPV of 20% (confirmation in 7/35 cases [95% CI 9.8%-36%]). For trisomy 18, the screen positive rate was 13/1592 (0.91%) and the pooled PPV 25% [95% CI 1.3%-90%]. The screen positive rate for trisomy 13 was 7/1592 (0.44%) and confirmed in 0/7 cases (pooled PPV 0% [95% CI 0%-100%]). The screen positive rate for additional findings was 23/767 (2.9%), of which none could be confirmed. No discordant negative results were reported. There is insufficient data to fully evaluate NIPT performance in pregnancies with a VT. However, existing studies suggest that NIPT can successfully detect common autosomal aneuploidies in pregnancies affected by a VT but with a higher false positive rate. Further studies are needed to determine the optimal timing of NIPT in VT pregnancies.

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.

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

ObjectiveThe 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 designRetrospective cohort study.MethodsA 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.ResultsIn 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.ConclusionsSingletons 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.

Should Vanishing Twin Pregnancies Be Systematically Excluded From Cell-Free Fetal DNA Testing?

(Abstracted from Prenat Diagn 2021;41:1241–1248) The goal of this study was to gain a better understanding of the impact of vanishing twins (VTs) on the incidence of discrepant cfDNA testing results. To do so, the researchers analyzed a series of cases of patients with VT to determine the extent to which this compromised cfDNA testing results.

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

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

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.

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

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? The timing of the demise of a co-twin after the registration of cardiac activity is an independent risk factor for adverse perinatal outcomes. 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. We retrospectively reviewed the medical records of 38876 singletons delivered from ART cycles between 2006 and 2018, at the Peking University Third Hospital. In total, 35188 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. 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). 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. 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. This study was supported by the National Natural Science Foundation of China for Young Scholars (Reference number: 31801251). No competing interests to declare. not applicable.

First-trimester screening for trisomies in pregnancies with vanishing twin.

To examine multiples of the median (MoM) values of serum free beta-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) in a large series of pregnancies with a vanishing twin, determine the association of these values with the interval between embryonic death and blood sampling, and develop a model that would allow incorporation of these metabolites in first-trimester combined screening for trisomy. This was a retrospective study comparing maternal serum free β-hCG and PAPP-A levels at 11-13 weeks' gestation in 528 dichorionic pregnancies with a vanishing twin, including 194 (36.7%) with an empty gestational sac and 334 (63.3%) with a dead embryo, with those in 5280 normal singleton pregnancies matched for method of conception and date of examination. In vanishing-twin pregnancies with a dead embryo, marker levels were examined in relation to the estimated time between embryonic death and maternal blood sampling. First, in pregnancies with a vanishing twin, median free β-hCG MoM was not significantly different from that in normal singleton pregnancies (1.000; 95% CI, 0.985-1.016 vs 0.995; 95% CI, 0.948-1.044; P = 0.849). Second, PAPP-A MoM was higher in vanishing-twin pregnancies than in normal singleton pregnancies (1.000; 95% CI, 0.985-1.015), both in the group with an empty gestational sac (1.165; 95% CI, 1.080-1.256; P = 0.0001) and in that with a dead embryo (1.175; 95% CI, 1.105-1.249; P < 0.0001). Third, in vanishing-twin pregnancies with a dead embryo, PAPP-A MoM was related inversely to the interval between estimated gestational age at embryonic demise and blood sampling (P < 0.0001). Fourth, in first-trimester screening for trisomy 21 in singleton pregnancies, the estimated detection rate, at a 5% false-positive rate, was 82% in screening by a combination of maternal age and fetal nuchal translucency thickness, and this increased to 86% with the addition of serum free β-hCG and to 91% with the addition of serum PAPP-A. Fifth, similar performance of screening can be achieved in pregnancies with a vanishing twin, provided the appropriate adjustments are made to the level of PAPP-A for the interval between estimated gestational age at embryonic demise and blood sampling. First-trimester screening for trisomy in pregnancies with a vanishing twin should rely on a combination of maternal age, fetal nuchal translucency thickness and serum free β-hCG, as in singleton pregnancy, without the use of serum PAPP-A. Alternatively, PAPP-A can be included but only after appropriate adjustment for the interval between estimated gestational age at fetal demise and blood sampling. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

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

To evaluate whether vanishing twin (VT) pregnancies following spontaneous conception have a more adverse perinatal outcome than those conceived after assisted reproduction techniques. 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). 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. IVF/ICSI poses a higher risk for an adverse perinatal outcome following VT pregnancies as compared with those spontaneously conceived.

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

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

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

To evaluate whether vanishing twin (VT) pregnancies achieved by invitro fertilization and intracytoplasmic sperm injection (IVF-ICSI) had a more adverse perinatal outcome than those after natural conception. Longitudinal, retrospective cohort study. Tertiary university hospital. Three hundred and six (78 after IVF-ICSI and 228 after natural conception) VT pregnancies over a 22-year period, with VT cases matched to primarily singleton controls. None. Obstetric and neonatal outcome data. The incidence of VT was statistically significantly higher after natural conception (18.2% of twins) than after IVF-ICSI (12.6% of twins). The odds of VT in pregnancies complicated with pregestational or gestational diabetes were disproportionally higher in IVF-ICSI cases than in spontaneously conceived VT pregnancies (adjusted odds ratio [AOR]: 0.80 vs. 3.10 and 1.00 vs. 1.07, respectively). Previous induced abortion (AOR 1.34) or second-trimester fetal loss (AOR 3.3) increased the risk of VT pregnancies after spontaneous conception. Gestational diabetes mellitus in both the previous (AOR 5.41) and the present (AOR 2.3) pregnancy as well as chronic maternal diseases (AOR 3.5) and placentation anomalies all represented independent risk factors for VT after IVF-ICSI. Vanishing twin pregnancies had a lower prevalence and a worse perinatal outcome after IVF-ICSI as compared with those of their spontaneously conceived counterparts.

Early beta-human chorionic gonadotropin trends in vanishing twin pregnancies

To describe the early β-hCG trends in vanishing twins compared with normally progressing singleton and twin pregnancies. Retrospective cohort study. University-based infertility clinic. Women undergoing fresh IVF/intracytoplasmic sperm injection (ICSI) cycles between 1998 and 2010. Early β-hCG level increase in vanished twin pregnancies was compared with the level increase in normally progressing singleton and twin pregnancies. Two-day percent increase in β-hCG level. Pregnancies with vanishing twins demonstrated a significantly lower mean 2-day percent increase in β-hCG level than singletons and twins (114.3% vs. 128.8% and 125.4%, respectively). Vanishing twins arresting at earlier developmental stages demonstrated significantly further reduced β-hCG level increases. Infrequently, all groups had β-hCG level increases less than previously established clinical thresholds that led to a live birth. Early β-hCG level increases are slower in vanishing twins than in singleton and twin pregnancies, with the slowest increases seen when the spontaneous fetal losses occur at earlier developmental stages. All increases, however, are within clinically accepted normal limits. Therefore, abnormal β-hCG level increases should not be attributed to a vanishing twin. Of note, an abnormal β-hCG level trend--even an initial decrease--does not preclude live birth, even in a singleton pregnancy.

Gonadotrophin ovulation induction and enhancement outcomes: analysis of more than 1400 cycles

Ovulation induction (OI) or ovulation enhancement (OE) with gonadotrophins can be a reasonable treatment option for patients with a variety of infertility diagnoses. It must be used with extensive monitoring and management given the risk of multiple pregnancy, especially high-order multiples. This retrospective study evaluated per cycle outcomes of a large cohort of 1452 gonadotrophin OI/OE cycles at an academic infertility centre, and the efficacy of specific guidelines in limiting multiple pregnancy. The lowest possible gonadotrophin doses were used and cycle cancellation was recommended if more than three dominant follicles were present, and/or if serum oestradiol was above 1500 pg/ml. Overall, pregnancy rate (PR) was 12% and live birth rate was 7.7%, with an increasing trend in younger patients ( P = 0.0002 and <0.0001, respectively). Multiple clinical PR was 2.6% with 1.9% twins and 0.7% triplets and above. The birthweight of a singleton from a vanishing twin pregnancy ( n = 8) was significantly lower than other singletons (2882 g versus 3250 g, P = 0.013). Reducing multiple pregnancies from OI/OE cycles remains an important and challenging goal. In this large cohort, high-order multiple clinical PR was limited to 0.7% per cycle by using specific management strategies while maintaining a reasonable PR. High-order multiple pregnancy and live birth may be limited with the use of certain management guidelines in gonadotrophin ovulation induction and enhancement cycles while maintaining a reasonable pregnancy rate. Those guidelines include using the lowest possible dose of gonadotrophins, and cycle cancellation if more than three dominant follicles are present and/or if the oestradiol concentration is >1500 pg/ml.

First trimester aneuploidy screening in the presence of a vanishing twin: implications for maternal serum markers

To assess the impact of a vanishing twin on the levels of the biochemical markers used in the first trimester aneuploidy screening. A retrospective analysis of free beta-hCG and PAPP-A levels in 270 women with a normal singleton fetus with ultrasound evidence of a vanishing twin pregnancy. Marker levels (as MoM) were compared in three groups-76 women with a second empty gestational sac, 194 women with a second gestational sac containing a dead fetus with a measurable crown rump length (CRL), and 1360 matched singleton pregnancies. In women with a second empty gestational sac, the median free beta-hCG and PAPP-A MoMs (0.968 and 1.040, respectively) were not significantly different from the 1.0 MoM in singleton pregnancies. In the group with a vanished twin with a measurable-CRL-there was a significantly increased median PAPP-A MoM (1.317) but the median free beta-hCG MoM was not changed (1.024). Modelling this bias in PAPP-A MoM the detection rate for trisomy 21 would fall from 85 to 75%. First trimester screening in the presence of a vanishing twin may lead to errors in risk estimation. In such circumstances it may be advisable to restrict screening to the use of nuchal translucency (NT) alone.

The vanishing twin: prevalence and consequences for outcome after assisted reproduction

Since the first in vitro fertilization (IVF) baby was born in 1978, more than 1 million children have been born following assisted reproductive technology. During the 1990s, most European countries succeeded in reducing the incidence of triplet births; however, due to the double embryo transfer policy, twins still account for over 20% of the assisted reproductive technology children born. It is well known that the outcome of twins is poorer than for singletons; however, another consequence of double embryo transfer is that one in ten IVF singletons are born after a vanishing twin pregnancy. Two-thirds of these lose their co-twin during the first and second trimester, but even if spontaneous reduction onsets early in pregnancy this influences the survivor, as the surviving fetus carry higher neonatal risks including low birthweight, preterm birth, intrauterine growth retardation, neonatal deaths and admission to neonatal intensive care unit. Presumably, long-term outcomes such as cerebral palsy are also in...

Consequences of Vanishing Twins in IVF/ICSI Pregnancies

In Denmark, 4% of children at present are born by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Singleton IVF/ICSI infants are relatively likely to be preterm and have low birth weight. Spontaneous reductions may increase morbidity in singleton IVF infants. Previous work indicates that “vanishing” twins is not the only factor in adverse outcomes. The authors analyzed data on women with ongoing IVF/ICSI pregnancies that were detected by transvaginal sonography in gestational week 8. The goals were to determine the frequency of spontaneous reductions in IVF/ICSI twin pregnancies and to compare morbidity in survivors of a vanishing cotwin with both singletons and born twins. Included were 642 survivors of a vanishing cotwin, 5237 singletons from single gestations, and 3678 twins from twin gestations. Approximately 10% of all IVF singletons born resulted from a twin gestation in early pregnancy. On multiple logistic regression analysis, adjusting for maternal age, parity, and ICSI, the odds ratio (OR) for birth weight below 2500 g in singleton survivors of a vanishing twin was 11.7 (95% confidence interval [CI], 1.2–2.2), and for birth weight below 1500 g, it was 2.1 (95% CI, 1.3–3.6), compared with singletons resulting from single gestations. Corresponding figures were obtained for preterm births. The increased risk was almost entirely the result of reductions occurring after 8 weeks gestation. No increase in the risk of neurologic sequelae was found in survivors of a vanishing cotwin compared with singletons. The OR for cerebral palsy, however, was 1.9 (95% CI, 0.7–5.2). The later in pregnancy that spontaneous reduction began, the higher the risk of neurologic sequelae. The adjusted OR of child death was 3.6 (95% CI, 1.7–7.6) in survivors compared with the singleton cohort. These findings suggest that outcomes for IVF/ICSI survivors of a vanishing cotwin have poorer outcomes than singletons from single gestations. Because approximately 10% of IVF/ICSI singletons result from a vanishing twin pregnancy, this may explain the relatively adverse outcomes observed in IVF/ICSI singleton infants. These considerations favor elective single embryo transfer, which will reduce the high risk of twins and may also lessen the risk of spontaneous reduction and the poor outcomes associated with it.

Vanishing twin is associated with less favorable obstetric outcome compared to singleton pregnancies in women undergoing IVF-ET

COMPARED TO SINGLETON PREGNANCIES IN WOMEN UNDERGOING IVF-ET SONYA ABDEL-RAZEQ, MOHAMED MITWALLY, LAURA DETTI, MICHAEL SULLIVAN, KENT CRICKARD, MICHAEL DIAMOND, University at Buffalo, Gynecology and Obstetrics, Buffalo, New York, Wayne State University, Obstetrics and Gynecology, Bloomfield Hills, Michigan, Wayne State University, Department of Obstetrics and Gynecology, Detroit, Michigan, Wayne State University, Obstetrics/Gynecology, Detroit, Michigan OBJECTIVE: There is evidence that infertility treatment, including in vitro fertilization and embryo transfer (IVF-ET), is associated with less favorable obstetric outcome, specifically, higher pregnancy loss, preterm labor and low birth weight (BW). Vanishing-twin is a phenomenon in which one or more of implanted embryos fail to continue. We studied outcome of singleton pregnancies after vanishing-twin compared to pregnancies that started as singletons. STUDY DESIGN: Retrospective analysis of 61 consecutive live-births from singleton pregnancies in women undergoing IVF-ET. Five pregnancies started as twins and ended as singletons due to vanishing-twin; 56 pregnancies started as singletons. Vanishing-twin was diagnosed by ultrasound at 6-wks (2 gestational sacs with 2 heartbeats) followed by another ultrasound showing loss of one of the twins at 8 to 12 wks. Gestational age (GA) was calculated from ET day until delivery. BW was calculated as percentage from BW expected according to GA (expected BW was calculated from control population similar to Western New York region matching patients who underwent IVF-ET). RESULTS: Vanishing-twin pregnancies were associated with significantly lower BW and shorter GA. There was no significant difference regarding age, gravity, infertility factor and duration, ovarian stimulation protocol, or in vitro conditions (oocyte insemination, day and number of embryos transferred, fertilization or implantation rate). CONCLUSION: Pregnancies associated with vanishing-twin after IVF-ET are associated with higher risk for low BW and short GA.