A longitudinal study of low birthweight children: reproductive, perinatal, and environmental precursors of developmental status at three years of age.

The study includes all children (N = 62) with birthweight below 2000 grams, born within a 15 months period at a municipal hospital in Oslo, Norway. Since there are no private hospitals, and home births are almost non-existent, children born at the municipal hospital constitute a cross-section of the population. Low birthweight children made up 2.3% of all births in the hospital during the 15-month period. A wide range of medical data concerning pregnancy, delivery, and the perinatal period was collected. On the basis of these data an optimality index was determined for each child. Intellectual assessments were made at 3, 6, 9, 12, 18, and 36 months. Observation of the home environment was made at 6 months. Parents were interviewed about their children's behavioral problems, the language skills were assessed, at 36 months. Children who at 3 years of age had poor performance on the Stanford-Binet and on the Reynell receptive scale, were among those who had had a low optimality index. The optimality index did not discriminate children with low scores on the Reynell expressive scale, spontaneous to MLU, and the behavioral questionnaire. Children with a low optimality index, but who performed well on the Stanford-Binet and on the Reynell receptive scale had higher SES, as compared with children with a low optimality index who had poor performance on these measures at 3 years. Therefore environmental factors may modate the influences of reproductive and perinatal risk.