Prevalence of congenital heart defects in monochorionic/diamniotic twin gestations: A systematic literature review

Abstract

Objective. Congenital heart defects (CHDs) affect approximately 0.5% of all neonates. Recent literature points to a possible increase in the CHD prevalence among monochorionic/diamniotic (MC/DA) twin gestations. We hypothesized that MC/DA twin pregnancy is a risk factor for CHD. Methods. A systematic review of all published English literature was conducted on MEDLINE (Ovid and PubMed) from January 2000 through April 2007 using the medical subject heading terms "congenital heart defect" and "monozygotic twins." Four observational studies were included in the final analysis. Published historical data were used for the population background risk of CHD. Relative risk (RR) estimates with 95% confidence intervals (CIs) were calculated by fixed and random effect models. Results. We included a total of 40 fetuses with CHDs among 830 fetuses from MC/DA twin gestations. Compared with the population, CHDs were significantly more prevalent in MC/DA twins regardless of the presence of twin-twin transfusion syndrome (TTTS) (RR, 9.18; 95% CI, 5.51-15.29; P