Purpose: to demonstrate the types of fetal malformations in multiple pregnancy and their relation to chorionicity. Methods: one hundred and sixty-nine multiple pregnancies were evaluated. In all cases prenatal ultrasound examination was performed during antenatal care. Chorionicity was defined by: first trimester ultrasound evaluation (absence of lambda sign); presence of two separate placentas; different fetal sex; pathological placental examination. Results: twenty-four (14.2%) fetal malformations were observed, 22 in twin and 2 in triplet pregnancy. In the group with fetal malformations 13 were monochorionic, 4 dichorionic and in 5 the chorionicity was unknown. Some malformations were unique to twins (conjoined twins n = 5, acardiac twin n = 3) and others were nonunique to twins. The gestational age at delivery was lower in the group with fetal malformations compared to the group without fetal malformations. Conclusion: the majority of malformations occurred in the monochorionic pregnancies. In multiple pregnancies early determination of chorionicity is helpful to establish the prognosis and to plan the management of pregnancy.
Multiple pregnancy; Fetal malformations; Chorionicity; Ultrasound; Placenta
