Twin Pregnancies Conceived by Assisted Reproductive Technology: Maternal and Perinatal Outcomes

Association between chorionicity and preterm birth in twin pregnancies: a systematic review involving 29 864 twin pregnancies

BACKGROUND

The perinatal mortality and morbidity among twins vary by chorionicity. Although it is considered that monochorionicity is associated with an increased risk of preterm birth in twin pregnancies, no systematic review exists evaluating this association.

OBJECTIVES

This systematic review was undertaken to assess the association between preterm birth and chorionicity in twin pregnancies.

SEARCH STRATEGY

We searched the electronic databases from January 1990 to July 2019 without language restrictions.

SELECTION CRITERIA

All studies on twin pregnancies where chorionicity and preterm birth were evaluated were included.

DATA COLLECTION AND ANALYSIS

Findings are reported as odds ratios with 95% confidence intervals. The estimates are pooled using random-effects meta-analysis.

MAIN RESULTS

From 13 156 citations, we included 39 studies (29 864 pregnancies). Monochorionicity was significantly associated with increased risk of preterm birth at ≤28, ≤32, ≤34 and <37 weeks in women asymptomatic and symptomatic for preterm labour (odds ratio [OR] 2.14, 95% CI 1.52-3.02, I²  = 46%, OR 1.55, 95% CI 1.27-1.89 I²  = 68%, OR 1.47, 95% CI 1.27-1.69, I²  = 60%, OR 1.66, 95% CI 1.43-1.93, I²  = 65%, respectively). Among those asymptomatic for preterm labour, significantly increased odds of preterm birth were seen for monochorionicity at gestations ≤34 weeks (OR 1.85, 95% CI 1.42-2.40, I²  = 25%) and <37 weeks (OR 1.75, 95% CI 1.22-2.53, I²  = 61%). Sensitivity analysis showed significantly increased odds of spontaneous preterm birth at ≤34 and <37 weeks for monochorionicity (OR 1.25, 95% CI 1.01-1.55, I²  = 0% and OR 1.41, 95% CI 1.13-1.78, I²  = 0%).

CONCLUSIONS

Monochorionicity is significantly associated with preterm birth at all gestations.

TWEETABLE ABSTRACT

In twin pregnancies, monochorionicity is associated with an increased risk of preterm birth at all gestations.

Congenital Malformations in Infants of Mothers Undergoing Assisted Reproductive Technologies: A Systematic Review and Meta-analysis Study

Objectives

This meta-analysis aimed to evaluate congenital malformations in infants conceived by assisted reproductive techniques (ART), compared with infants conceived spontaneously.

Methods

In this study, available resources searched to find relevant articles included PubMed, ScienceDirect, Scopus, Google Scholar, Cochrane, ProQuest, Iranmedex, Magiran, and Scientific Information Database. After extracting the necessary information from evaluated articles, meta-analysis on the articles’ data was performed using Stata version 11.2.

Results

In this study, from a total of 339 articles, extracted from the initial investigation, ultimately 30 articles were selected for meta-analysis that assessed the use of ART on the risk of congenital abnormalities and some birth complications on 5 470 181 infants (315 402 cases and 5 154 779 controls). The odds ratio (95% confidence interval [CI]) for low birth weight was 1.89 (95% CI, 1.36 to 2.62), preterm labor 1.79 (95% CI, 1.21 to 2.63), cardiac abnormalities 1.43 (95% CI, 1.27 to 1.62), central nervous system abnormalities 1.36 (95% CI, 1.10 to 1.70), urogenital system abnormalities 1.58 (95% CI, 1.28 to 1.94), musculoskeletal disorders 1.35 (95% CI, 1.12 to 1.64), and chromosomal abnormalities in infants conceived by ART was 1.14 (95% CI, 0.90 to 1.44), which were all statistically significant, except chromosomal abnormalities.

Conclusions

The risk of congenital abnormalities and some birth complications were significantly higher in ART than normal conception, while chromosomal abnormalities were not; therefore, the application of ART should be selected individually for patients by detailed assessment to reduce such risks in the population.

Assisted reproductive technology and risk of congenital malformations: a meta-analysis based on cohort studies

PURPOSE

To assess the association between assisted reproductive technology (ART) and risk of congenital malformations (CM) by conducting a meta-analysis of cohort studies.

METHODS

PubMed, Google Scholar, Cochrane Libraries and Chinese database were searched through August 2014 to identify studies that met pre-stated inclusion criteria. Either a fixed- or a random-effects model was used to calculate the overall combined risk estimates. Subgroup analysis was performed to explore potential heterogeneity moderators.

RESULTS

Fifty-seven studies involving 119,874 infants conceived following ART and 1,212,320 infants conceived naturally were included in the analysis. The ART-conceived infants were associated with a higher risk of CM [relative risk (RR) = 1.33; 95 % confidence interval (CI) 1.24-1.43] when compared with those conceived naturally. When data were restricted to singleton births (RR = 1.38; 95 % CI 1.30-1.47), major CM (RR = 1.47; 95 % CI 1.29-1.68), matched/adjusted studies (RR = 1.37; 95 % CI 1.27-1.47) or high quality studies (RR = 1.40; 95 % CI 1.27-1.55), the increased risk of CM still existed in ART pregnancies. Additionally, an increased risk of CM was also found when the ART twin (RR = 1.18; 95 % CI 1.06-1.32) or multiple births (RR = 1.16; 95 % CI 1.05-1.27) were separately compared with spontaneously conceived twin or multiple births. Substantial heterogeneity was observed across studies (I (2) = 68, 44, 39, and 33 % for all infants, singletons, twins and multiples, respectively). Whether confounding factors were matched or adjusted, study quality and sample size as the first three of the most relevant heterogeneity moderators have been identified. No evidence of publication bias was observed (P > 0.10).

CONCLUSIONS

The ART-conceived infants have a higher risk of CM compared with those conceived naturally. However, these estimates have to be viewed with caution because of heterogeneity.