The relationship between major anomalies and chorionicity in twin pregnancies referred for first trimester and second trimester detailed anatomic ultrasonography.

Abstract

Objectives: The purpose of this study is to validate the relationship between chorionicity and congenital anomalies.

Material and methods: A retrospective analysis twin pregnancies that underwent ultrasonographic fetal anatomy screening in the first or second trimester was conducted. Analyzed variables were, gestational age, chorionicity, presence of major fetal structural anomalies, number of affected fetuses, anomaly type, and use of assisted reproductive techniques (ART).

Results: Of the 824 twin pregnancies included in the study, 116 (14%) had major fetal anomalies. The frequency of major fetal structural anomalies was higher in monochorionic (MC) twin pregnancies compared to dichorionic (DC) twin pregnancies (p < 0.001). When anomalies were categorized into cardiac, central nervous system, and other system anomalies, no significant correlation was found between chorionicity and anomaly groups (p = 0.794).

Conclusions: In MC twin pregnancies, major fetal structural abnormalities are more prevalent. Prioritizing the evaluation of chorionicity is essential due to the increased risk associated with twin pregnancies.