Biochemical maturation of the guinea pig lung and survival following premature delivery

1. Viable preterm guinea pigs were delivered by Caesarean section from 62 day gestation (term = 68 days). 2. Survival rates (24 hr) were greater than 90%, greater than 55% and greater than 35% respectively at 65, 63 and 62 days gestation. Guinea pig pups experienced increasing respiratory difficulty with progressive prematurity. 3. Lung phosphatidylcholine concentration increased steadily from 0.52 +/- 0.09 mumol/mg DNA at day 50 to 3.9 +/- 0.5 mumol/mg DNA at term. The relative contribution of the disaturated dipalmitoyl species increased over this time from 24.5 to 42.9%. 4. Pulmonary antioxidant capacity increased markedly over the final eight days of gestation, individual increases being manganese superoxide dismutase 68%, copper/zinc superoxide dismutase 48%, glutathione peroxide 37% and catalase 198%