Hyaline membrane disease, birth weight, and gestational age. Effects on development in the first two years.

Mean mental and motor developmental test scores (Bayley scales) at 4, 12, and 24 months of age were determined for 161 graduates of a neonatal intensive care unit during the period 1977 through 1979. Analysis of variance for our data showed significant effects of hyaline membrane disease (HMD) on mental and motor development at 4 months, but disappearance of these effects at 12 and 24 months of age. Conversely, birth weight was not significantly related to developmental performance at 4 months, but was strongly related to both mental and motor performance at 12 and 24 months of age. Gestational age was significantly related to mental performance at 24 months of age. No relationship was found between HMD and major CNS handicapping conditions; both birth weight and gestational age were highly related to the occurrence of neurologic handicaps. Of the three variables assessed, birth weight was the best predictor of neurodevelopmental outcome.