Spontaneous loss of a co-twin and the risk of birth defects after assisted conception

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.

A Dual Gender Rare Case with 47,XY, + 18/46,XX Karyotype: Chimera or Mosaic?

Our objective is to report one rare case of dual gender chimerism involving abnormal male trisomy 18 and normal female karyotype. The baby was born full term with birth weight of 1.8 kg, not vigorous with light meconium stained liquor and Apgar score of 51, 85 and 910. Parents are 40 years old and mother is G6P5 + 1. The baby had clinical features of Edwards syndrome, and a blood sample was sent to Human Genome Centre, Universiti Sains Malaysia, Malaysia for cytogenetic analysis. Conventional cytogenetic analysis results showed two distinct sex discordant genetic cell lines XY and XX in 90:10 ratio. The male genetic cell line XY also showed trisomy 18 (47,XY, + 18) consistent with clinical diagnosis of male Edwards syndrome, whereas the second genetic cell line showed normal 46,XX female. The present case was reported as dual gender chimera with chi 47,XY, + 18/46,XX karyotype pattern. To the best of available knowledge, dual gender chimerism with abnormal male trisomy 18 and normal female karyotype has not been reported so far, and this case is reported for its rarity and as the first report.

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.

Intellectual Disability in Children Conceived Using Assisted Reproductive Technology

OBJECTIVES

To examine whether children conceived using assisted reproductive technology (ART) have a higher risk of intellectual disability (ID) compared with non-ART-conceived children and describe known causes of ID in these groups.

METHODS

We linked ID and ART data from population-based registers in Western Australia. Our cohort included live births from 1994 to 2002 (n = 210 627) with at least 8 years of follow-up. The prevalence of ID was compared between ART- and non-ART-conceived children, and risk of ID was estimated using Poisson regression with robust SEs. We also stratified by plurality and gestation at delivery.

RESULTS

Children conceived using ART had a small increased risk of ID (risk ratio 1.58; 95% confidence interval 1.19-2.11) even when analyses were restricted to singleton births (risk ratio 1.56; 95% confidence interval 1.10-2.21). The risk of ID was more than doubled for those born very preterm, for severe ID, and after intracytoplasmic sperm injection (ICSI) treatments. Children conceived using ICSI had a greater risk of ID than those conceived using in vitro fertilization and were more likely to have a known genetic cause for ID (27.6% vs 12.9% in vitro fertilization and 11.9% non-ART).

CONCLUSIONS

The risk of ID was increased in children born after ART in Western Australia from 1994 to 2002. More recent cohorts should be examined to assess the impact of important changes in ART clinical practice. Our results are particularly pertinent because multiple embryo transfers are routinely performed in many countries, increasing the risk of preterm birth, and ICSI use rates are high.

Assisted reproductive technologies: a hierarchy of risks for conception, pregnancy outcomes and treatment decisions

The use of assisted reproductive technologies (ART) for the treatment of infertility has grown exponentially over the last 20 years, and now accounts for 4% of all births in Australia, and over 1 m births annually around the globe. There is consistent reporting of increased risk of adverse perinatal outcomes and birth defects following infertility treatment. However, change in practice has been stymied by critical knowledge gaps with regards to (a) the relative contribution of patient and treatment factors to adverse outcomes, (b) the independent contribution of specific contemporary treatments and treatment combinations to outcomes, (c) the impact of innovations in laboratory and clinical practice on treatment success and observed risk and (d) changes over time in patient characteristics. Here we summarize key findings from the South Australian Birth Cohort, which is a whole-of-population cohort of over 300,000 births from 1986 to 2002. Relative to spontaneous conceptions, singletons from assisted conception were more likely to be stillborn [odds ratio (OR)=1.82; 95% confidence interval (CI) 1.34-2.48], while survivors as a group were comprehensively disadvantaged at birth, including lower birth weight (OR=2109 g; 95% CI 2129-289), very low birth weight (OR=2.74; 95% CI 2.19-3.43), very preterm birth (OR=2.30; 95% CI 1.82-2.90) and neonatal death (OR=2.04; 95% CI 1.27-3.26). Major birth defects, including cardiac, urogenital and musculoskeletal defects are doubled after fresh ICSI cycles, which is a particular concern as ICSI now accounts for 70% of all treatment cycles globally. Future study is needed to provide contemporary, precise evidence to inform patient and clinic decision making, and generate knowledge for future innovation in ART laboratory methods and clinical practice, thereby optimizing treatment and health outcomes while reducing adverse events.

Cerebral palsy after assisted reproductive technology: a cohort study

AIM

To calculate the birth prevalence of cerebral palsy (CP) after assisted reproductive technology (ART) and compare the clinical outcomes of children with CP after ART or natural conception.

METHOD

This cohort study used linked CP and ART register data from live births in Western Australia (1994-2002). Birth prevalence was calculated and data analysed using descriptive statistics and logistic regression. It was adjusted for confounding variables and stratified by plurality and gestational age.

RESULTS

In total, 211 660 live births were included; prevalence of CP was increased in children born after ART (7.2/1000 live births compared with naturally conceived births, 2.5/1000). Odds of CP were doubled for singletons; when stratified by gestational age odds were only increased in the under 32-week group. Prevalence of CP was increased in ART (9.9/1000 live births) and naturally conceived twins (8.4/1000 live births). Clinical outcomes were similar between ART and naturally conceived children.

INTERPRETATION

The birth prevalence of CP is increased two-fold after ART. After stratification for gestational age and plurality, residual risk remains in singletons born very preterm. Birth prevalence of CP will be tracked over time to identify any impact of changes to clinical practice.

WHAT THIS PAPER ADDS

In Western Australia, assisted reproductive technology (ART) increases birth prevalence of cerebral palsy (CP), mediated mostly by preterm and multiple births. Preterm birth alone does not account for the doubled odds of CP for ART singletons born very preterm. Clinical outcomes are similar between ART and naturally conceived children with CP.

Vanishing twin syndrome among ART singletons and pregnancy outcomes

STUDY QUESTION

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

SUMMARY ANSWER

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

WHAT IS KNOWN ALREADY

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

STUDY DESIGN, SIZE AND DURATION

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

PARTICIPANTS/MATERIALS, SETTING, METHODS

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

MAIN RESULTS AND THE ROLE OF CHANCE

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

LIMITATIONS REASONS FOR CAUTION

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

WIDER IMPLICATIONS OF THE FINDINGS

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

STUDY FUNDING/COMPETING INTEREST(S)

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

TRIAL REGISTRATION NUMBER

N/A.