Perinatal factors and neonatal morbidity in twin pregnancy.

There were 177 pairs of twins reviewed. The incidence of twin pregnancy was 1:112.2 deliveries in a population consisting of 76.8 per cent Mexican-Americans. The incidence of breech, cesarean section, and assisted deliveries was higher in twins than singleton deliveries, and the incidence was higher in twin 2 than twin 1. Mortality rates, fetal and neonatal, were lower than those previously reported. Neonatal findings and complications include low Apgar scores, small-for-dates infants, hyaline membrane disease, hypoglycemia, hypocalcemia, hyperbilirubinemia, and congenital malformation. The increased incidence of deaths and morbidity in twin pregnancy, as compared to singleton pregnancy, was attributed to prematurity, and to complications and diseases pertaining to prematurity, rather than to twinning per se.