Duration and complications of multiple pregnancies.

Multiple pregnancies reach full term only in a remarkably lower percentage with respect to single pregnancies. Even in the case of multiparae, delivery occurs some three weeks before term. Complications may concern either pregnancy and puerperium or delivery. The former include (1) abortions, especially frequent in the case of monoplacental and monochorial pregnancies; (2) rarer events, such as hydramnios, placenta praevia, association of an ectopic pregnancy with an intrauterine pregnancy, molar degeneration of one egg with normal development of the other; (3) gestoses of the first and second trimester, more frequent than in single pregnancy; and (4) higher incidence, during puerperium, of hemorrhage, phlebitis, and uterine subinvolution. With respect to delivery, normal delivery only occurs in approximately 70% of twin pregnancies, the period of dilatation being generally longer than normal. Better assistance and techniques during labor and especially in the interval between delivery of first and second twin have remarkably reduced the higher mortality rate, especially for the second twin.