Congenital Anomalies in Multiple Pregnancy: A Literature Review

Abstract

Importance Multiple pregnancy is relatively common in many countries and is associated with various pregnancy complications, including preterm birth, low birth weight, and congenital anomalies. In particular, a poorer prognosis has been reported when congenital anomalies overlap with other pregnancy complications in multiple pregnancy compared with singleton pregnancy. Objective This study reviews the characteristics of congenital anomalies that occur in multiple gestations as compared with singleton pregnancies. Evidence Acquisition An extensive manual search of major electronic databases was conducted in June 2023. This literature review provides a comprehensive coverage of the congenital anomalies in multiple pregnancy. Results Most studies have shown that multiple gestations are associated with an increased risk of congenital anomalies compared with singleton pregnancies. In addition, higher rates of congenital anomalies and concordance have been observed in monozygotic versus dizygotic twins. The effect of assisted reproductive therapies on the risk of congenital anomalies appears to be smaller in multiple gestations than in singleton pregnancies. Conclusions Multiple pregnancy is significantly associated with an increased risk of congenital anomalies. Relevance This review provides obstetrical providers with the requisite knowledge to offer appropriate antenatal care and prenatal anomaly screening to patients with multiple pregnancies. Target Audience Obstetrics and gynecology specialists and family physicians. Learning Objectives After participating in this activity, the learners should be better able to explain the prevalence and trend of congenital anomalies in multiple pregnancy; describe the importance of zygosity in prevalence and concordance in multiple pregnancy; and describe the effect of assisted reproductive therapies on the risk of congenital anomalies.