Twin gestations: I. Antenatal care and complications.

In order to determine the occurrence of antenatal complications in twin pregnancies, we examined the medical records of 939 consecutive twin gestations delivered at Women's Hospital, Los Angeles County/University of Southern California Medical Center between 1980-1985. The rates of occurrence of the eight most common antenatal complications were determined and compared with their incidence in singleton gestations. In addition, complication rates were related to zygosity, levels of antenatal care, and time of antenatal diagnosis. Twin gestations had an 83% incidence of antenatal complications, in contrast to a 32% incidence in singleton gestations. The increased complication rate was due to the disproportionate increase in three complications: preterm labor, pregnancy-induced hypertension, and fetal death. Other complications did not occur more frequently in twin gestations than in singleton gestations. Monozygotic gestations were more frequently complicated by fetal death, and dizygotic gestations by pregnancy-induced hypertension.