Objective: To assess the effect of improved survival of increasingly premature infants by examining the outcomes at school age of a large group of children born at different birth weights.
Design: Inception cohort.
Setting/participants: Participants were selected from two previously studied multisite cohorts: very low-birth-weight (less than or equal to 1500 g) children referred to participating intensive care units and heavier birth-weight children drawn from a stratified random sample of births in geographically defined regions. Follow-up at 8 to 10 years of age was by a combination of telephone interview and home/clinic visits for 65.1% (1868) of those eligible.
Main outcome measures: The presence or absence of 17 specific conditions, limitations in activities of daily living due to health, mental health (affective health, behavior problems), and, for a subset, IQ scores.
Results: Decreasing birth weight was associated with an increased morbidity for all measures except affective health; those with birth weights of 1500 g or less were more likely to experience multiple health problems. Maternal educational attainment did not influence the association of birth weight with morbidity except for IQ among children whose birth weight was above 1000 g, for which socioeconomic disadvantage worsened the status of all children irrespective of birth weight.
Conclusions: Children born at lower birth weights experience increased morbidity at early school age. These results reinforce the importance of postdischarge, early intervention programs to reduce the risk of these later health problems.