Dataset Information

Vanishing twin syndrome among ART singletons and pregnancy outcomes.

ABSTRACT:

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.

SUBMITTER: Magnus MC

PROVIDER: S-EPMC5850786 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Publications

Vanishing twin syndrome among ART singletons and pregnancy outcomes.

Magnus Maria C MC Ghaderi Sara S Morken Nils-Halvdan NH Magnus Per P Bente Romundstad Liv L Skjærven Rolv R Wilcox Allen J AJ Eldevik Håberg Siri S

Human reproduction (Oxford, England) 20171101 11

<h4>Study question</h4>Among babies born by ART, do singleton survivors of a vanishing twin have lower birth weight than other singletons?<h4>Summary answer</h4>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.<h4>What is known already</h4>Previous studies indicate that ART singletons with VTS have increased risk of adver ...[more]

PMID: 29025107

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Project description:Research questionIs there an association between intrauterine hematoma (IUH), vanishing twin syndrome (VTS), and subsequent complications in twin pregnancies after in vitro fertilization (IVF)? What are the risk factors for these complications?DesignWomen who presented with two live gestational sacs following double embryo transfer were included. Patients with systematic diseases, artificial fetal reduction, and incomplete data were excluded. Further stratification of IUH pregnancies was performed according to IUH-related characteristics (i.e., volume, changing pattern, and relationship with fetal cardiac activities). The primary outcome was the incidence of VTS, while adverse outcomes in the surviving singleton and the gestational age of VTS were secondary outcomes.ResultsThe incidence of IUH was 13.8%. A total of 1,078 twin pregnancies including 539 IUH pregnancies and 539 non-IUH pregnancies were included. IUH pregnancy was associated with higher risks of VTS (26.9% vs. 18.7%, p = 0.001) as well as a higher incidence of preterm birth (p = 0.001, crude OR = 1.98, 95% CI 1.28-3.09, adjusted OR = 1.19, 95% CI 1.09-1.24), threatened abortion (p < 0.001, crude OR = 9.12, 95% CI 2.90-28.69, adjusted OR = 6.63, 95% CI 1.69-14.67), and postpartum hemorrhage (p = 0.024, crude OR = 3.13, 95% CI 1.09-8.99, adjusted OR = 1.16, 95% CI 1.08-1.32) in the surviving singleton. There was no significant difference in risks of other complications. The absence of fetal cardiac activities at the diagnosis of IUH predicted VTS (p < 0.001, crude OR 4.67, 95% CI 3.67-5.78, adjusted OR 3.33, 95% CI 1.56-5.14) and fetal loss at smaller gestational age (7.81 ± 2.10 vs. 11.39 ± 5.60 weeks, p < 0.001), while an IUH with an increasing volume did not increase the risk of VTS but might induce threatened abortion in the surviving fetus (p < 0.001, crude OR 1.84, 95% CI 1.32-2.55, adjusted OR 1.72, 95% CI 1.13-2.13).ConclusionsIUH was a risk factor for VTS in twin pregnancies following double embryo transfer and elevated the risks of threatened abortion, preterm birth, and postpartum hemorrhage in the surviving singleton. The absence of fetal cardiac activities at the diagnosis of IUH elevated the risks of VTS, while an IUH with an increasing volume was associated with threatened abortion without elevating the risks of VTS. An IUH diagnosed before the presence of fetal cardiac activities also resulted in an earlier miscarriage. The study suggests that attention be paid to twin pregnancies with first-trimester IUH to prevent VTS and subsequent adverse perinatal outcomes.HighlightsFirst-trimester intrauterine hematoma (IUH) following double embryo transfer is associated with a higher incidence of vanishing twin syndrome (VTS) and elevated subsequent risk of threatened abortion, preterm birth, and postpartum hemorrhage in the surviving singleton. Other perinatal outcomes were not associated with the diagnosis of first-trimester IUH. The absence of fetal cardiac activities at the diagnosis of IUH was of predictive value toward VTS, while an IUH with an increasing size was associated with threatened abortion without elevating the risk of VTS. Incomplete fetal cardiac activities and earlier detection of an IUH might also predict miscarriage at smaller gestational age.

Project description:BackgroundTwin-to-twin transfusion syndrome (TTTS) is a serious complication of 10-15% of twin or triplet pregnancies in which multiple fetuses share a single placenta. Communicating placental vessels allow one fetus (the donor) to pump blood to the other (the recipient). Mortality rates without intervention are high, approaching 100% in some series, with fetal deaths usually due to cardiac failure. Surgical correction using laser photocoagulation of communicating placental vessels was developed in the 1980s and refined in the 1990s. Since it was introduced in Victoria in 2006, laser surgery has been performed in approximately 120 pregnancies. Survival of one or more fetuses following laser surgery is currently > 90%, however the neurodevelopmental outcomes for survivors remain incompletely understood. Prior to laser therapy, at least one in five survivors of TTTS had serious adverse neurodevelopmental outcomes (usually cerebral palsy). Current estimates of neurological impairment among survivors following laser surgery vary from 4 to 31% and long-term follow-up data are limited.MethodsThis paper describes the methodology for a retrospective cohort study in which children aged 24 months and over (corrected for prematurity), who were treated with laser placental photocoagulation for TTTS at Monash Health in Victoria, Australia, will undergo comprehensive neurodevelopmental assessment by a multidisciplinary team. Evaluation will include parental completion of pre-assessment questionnaires of social and behavioural development, a standardised medical assessment by a developmental paediatrician or paediatric neurologist, and age-appropriate cognitive and academic, speech and fine and gross motor assessments by psychologists, speech and occupational therapists or physiotherapists. Assessments will be undertaken at the Murdoch Children's Research Institute/Royal Children's Hospital, at Monash Health or at another mutually agreed location. Results will be recorded in a secure online database which will facilitate future related research.DiscussionThis will be the first study to report and evaluate neurodevelopmental outcomes following laser surgery for twin-to-twin transfusion syndrome in Victoria, and will inform clinical practice regarding follow-up of children at risk of adverse outcomes.

Project description:Transabdominal cerclage (TAC) is reported to be effective for preventing preterm birth in women with unsuccessful transvaginal cerclage (TVC) history. However, TAC has rarely been performed in twin pregnancy given the lack of sufficient evidence and the technical difficulty of the operation. Thus, it is unclear whether TAC is an effective procedure for twin pregnancy in women with a history of unsuccessful TVC. The aim of this study is to compare the characteristics and pregnancy outcomes after TAC in twin pregnancy versus singleton pregnancy, to examine whether twin pregnancy is a risk factor for very preterm birth (before 32 weeks) after TAC, and to determine whether TAC is effective in preventing preterm birth in twin pregnancy. This single-center retrospective cohort study included women who underwent TAC because of unsuccessful TVC history between January 2007 and June 2018. Of 165 women who underwent TAC, 19 had twins and 146 had singletons. Our results showed that the neonatal survival rate improved dramatically when TAC was performed (15.4% (prior pregnancy) vs 94.0% (after TAC) in twins, p<0.01; 22.8% (prior pregnancy) vs 91.1% (after TAC) in singletons, p<0.01). Moreover, the risk of very preterm birth was significantly decreased after TAC in both groups (36/39 (92.3%) (prior pregnancy) vs 2/19 (10.5%) (after TAC) in twins, p<0.01; 290/337 (86.1%) (prior pregnancy) vs 17/146 (11.6%) (after TAC) in singletons, p<0.01). More advanced maternal age and history of prior preterm delivery between 26+0 and 36+6 weeks were independently associated with very preterm birth, whereas the presence of a twin pregnancy was not associated with very preterm birth on multivariate logistic regression analysis. These results suggest that TAC is associated with successful prevention of very preterm birth and improved neonatal survival rates in the absence of procedure-related major complications in women with twin pregnancy and previous unsuccessful TVC history.

Dataset Information

Vanishing twin syndrome among ART singletons and pregnancy outcomes.

Study question

Summary answer

What is known already

Study design, size and duration

Participants/materials, setting, methods

Main results and the role of chance

Limitations reasons for caution

Wider implications of the findings

Study funding/competing interest(s)

Trial registration number

Publications

Vanishing twin syndrome among ART singletons and pregnancy outcomes.

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