Abstract
Monochorionic (MC) twins are at an increased risk of developing congenital heart defects (CHDs) compared to singletons and dichorionic twins. The development of acquired CHDs in this specific group of twins is associated with twin–twin transfusion syndrome (TTTS). We performed a systematic review and meta-analysis to provide an overview of the reported birth prevalence of CHDs in liveborn MC twins with and without TTTS. Twelve studies were included in this review. Compared to the reference population, MC twins were 6.3 times more likely to be born with a CHD (59.3 per 1000 liveborn twins; relative risk (RR) 6.3; 95% confidence interval (CI): 4.4–9.1), and TTTS twins had a 12-fold increased risk of having a CHD at birth (87.3 per 1000 live births; RR 12.4, 95% CI: 8.6–17.8). The increased incidence of CHDs can mainly be attributed to the risk of right ventricular outflow tract obstruction (35/1000 TTTS twin live births vs. 0.5/1000 singleton live births). We recommend an expert fetal echocardiogram in all MC twins, follow-up scans in the event of TTTS, and a postnatal cardiac evaluation in all TTTS survivors.
Highlights
Congenital heart defects (CHDs) represent the most common human birth defect, having a birth prevalence of 7–9 per 1000 singleton live births [1,2]
The birth prevalence of MC twins with a CHD may be influenced by the improved survival rates for MC twins over the last decade, especially for those treated for twin–twin transfusion syndrome (TTTS) [7]
Six studies included MC twin pregnancies complicated by TTTS only
Summary
Congenital heart defects (CHDs) represent the most common human birth defect, having a birth prevalence of 7–9 per 1000 singleton live births [1,2]. CHDs are more common in twin pregnancies with a reported prevalence of approximately 20 in 1000 live births. A systematic review and meta-analysis of four studies conducted in 2007 showed a 9-fold increase in CHD risk in MC twins [3] compared to singletons. The birth prevalence of MC twins with a CHD may be influenced by the improved survival rates for MC twins over the last decade, especially for those treated for TTTS [7].
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