Two studies were done. In the first, 51 infants from high-risk pregnancies were evaluated for accelerated clinical neurological maturation. Eight infants had accelerated neurological maturation 3 or more weeks in excess of gestational age. In the second study, a sample of 25 infants with documented acceleration of pulmonary surfactant (lecithin/sphingomyelin ratio greater than or equal to 2 at gestational age less than or equal to 32 weeks) all infants showed accelerated neurological maturation (range 3 to 8 weeks) with the conditions studied associated with accelerated pulmonary maturation (for instance, retroplacental bleeding, prolonged rupture of membranes, placental infarction, severe toxemia, hypertensive disease, circumvallation, and amnionitis). Chronic retroplacental bleeding was associated with the most dramatic pulmonary and neurological accelerations.