Does cesarean section protect against intraventricular hemorrhage in preterm infants?

A declining incidence of periventricular-intraventricular hemorrhage (PV-IVH) in preterm infants less than 35 weeks' gestational age during the years 1980 through 1987 led us to investigate the role of the route of delivery. Routine cephalic ultrasound was used to detect PV-IVH in 490 vaginal and 411 cesarean section deliveries. A lower incidence of all PV-IVH and severe PV-IVH was noted in cesarean section deliveries for each 2-year period, with a decline in all PV-IVH in vaginal and cesarean section deliveries from 39% and 31%, respectively, in 1980-1981 to 23% and 11% in 1986-1987. Striking differences were noted for infants less than 1500 g, less than 1000 g, or less than 27 weeks' gestation. For example, in infants less than 1000 g, the incidence of all PV-IVH was 52% in vaginal (n = 101) and 25% in cesarean section deliveries (n = 88), and of severe PV-IVH was 26% and 11%, respectively. These differences did not seem to be influenced by presence or absence of labor, breech presentation, or low Apgar scores. Route of delivery should be considered as an important variable in pharmacologic intervention studies.