Respiratory distress syndrome of the newborn and complications of pregnancy.

A group of 412 infants with birthweights between 501 and 2,500 gm and gestational ages of 36 weeks or less were studied for the influence of both prolonged ruputre of amniotic membranes and maternal hypertension on the incidence of idiopathic respiratory distress syndrome (IRDS). The occurrence of these complications was associated with a significant decrease in the incidence of IRDS only in infants with birthweights between 1,501 and 2,500 gm (37.4% in the no complications group versus 12.8% in the complications group; P less than .01) or gestational ages of 33 to 36 weeks (35.2% in the no complications group versus 13.1% in the complications group; P less than .01). In infants with birthweights of 1,500 gm or less or gestational ages of 32 weeks or less, the specific antecedent complications of pregnancy did not alter the incidence of IRDS. Rupture of the membranes for more than 72 hours had no greater effect on the incidence of IRDS than those lasting 24 to 72 hours.