Twin gestation: Is there a correlation between the location of the gestational sacs at the beginning of pregnancy, and the order of delivery

Objectives: To determine whether there is a dynamic in the location of amniotic sacs in a twin gestation, during pregnancy. Study Design: The study group comprised 63 twin pairs discordant for sex, who by vaginal sonography performed between 14 and 16 weeks' gestation, were characterized as first twin (opposite the internal os), and second twin. The order of delivery was recorded in the pregnancies that ended with vaginal birth. Results: Thirty seven of 41 (90.2%) twins who were delivered vaginally (between 32 and 41 weeks' gestation), were born in the same order as that predicted by transvaginal sonography early in pregnancy. It was found that in this small series there was a dynamic in the amniotic sac location in twin gestations during pregnancy in only about 10% of the cases. Conclusions: In roughly 90% of twins, there is no dynamic in the location of the amniotic sacs during pregnancy, and the first twin at the beginning of pregnancy intrinsically remains.