Advanced ultrasonic placental maturation in twin pregnancies

The mean length of twin pregnancies is shorter than that of singleton pregnancies. The possibility that the shorter gestation of twins is associated with advanced fetal maturational changes was studied in relation to placental maturation. For this purpose, the sonographically determined placental gradings of 158 twin pregnancies and 474 singleton pregnancies were compared at different gestational ages. The percent distributions of placental grades, from I to III, were significantly different throughout the third trimester, with a preponderance of Grade III placentas in the twin group (p less than 0.001). Considering the reported association of Grade III placentas with advanced gestation as well as fetal lung maturity, the present study suggests earlier maturational changes in twin fetuses compared with singleton fetuses.