On the cause of the retardation of fetal growth in multiple gestations.

The birthweights and placental weights of 3000 singletons, 1500 twin pairs and 67 triplets are studied in relation to the gestational age. From 30-32 weeks onwards, newborns of twin- and triplet gestation show lower birthweight as compared to singleton newborns. Placental indices (placental weights related to birthweights) are about alike in singletons, twins and triplets. From about 24 weeks onwards placental weights of twin and triplet newborns are smaller as compared to those of singletons. Obviously, children in multiple gestations become growth retarded, preceded by and very likely due to poor early placental development (placental crowding of the uterus).