An old problem revisited--hyaline membrane disease and Cesarean section.

The incidence of hyaline membrane disease (HMD) was investigated retrospectively in 159 preterm infants below 35 weeks gestation, weighing less than 2,000 g, and born during the 5-year interval 1975-79. The incidence of HMD was compared between infants delivered by elective Cesarean section, Cesarean section after the onset of labor and by the vaginal route. A significant difference (P less than 0.001) was found in the frequency of HMD dependent on the mode of delivery; 50% of infants delivered by elective Cesarean section developed HMD versus 19.2% in the vaginally delivered group. In infants delivered vaginally premature rupture of membranes (PROM) lowered the incidence of HMD to 5% compared to 32.4% in infants without PROM (P less than 0.01). When infants (less than 2,000 g) delivered vaginally without PROM were compared with those delivered by elective Cesarean section, no difference in HMD-incidence was observed. Out of 43 infants with birthweight above 2,000 g, who developed HMD during the 5-year period the majority had been delivered by elective Cesarean section. The possible effect of fetal stress on lung maturation is discussed.