Preterm infants with low birth weights (LBW) are likely to be smaller, have more health problems and lower academic achievement than full-term normal birth weight peers. The Infant Health and Development Program (IHDP) targeted LBW children for a variety of interventions and followed them over many years (some up to 18) to compare their educational achievement and cognitive function to those of their peers. However, in none of those studies was growth examined as an outcome.
This study followed 985 LBW infants who were randomly assigned to either an intervention group or a control group at birth. There were no differences in size or weight among the two cohorts at the time they were randomized. The intervention, which lasted until the babies were 36 months old, consisted of home visits, attendance at an educational center (a maximum of up to six hours per day, five days a week for two years), parent meetings and up to two meals a day. No nutritional counseling was offered. Children were considered to have received the intervention no matter how much or little parents made use of the services offered. There were no differences in number of children enrolled in school between the intervention and control groups at age four.
Eight hundred and seventy-eight children were evaluated at age eight. Retention was similar in both groups, between 88 and 89 percent. Children in the intervention group were longer and had larger head circumferences than children in the control group. Body Mass Index (BMI) differences were not statistically significant. Effects were greatest in children who started out with the lowest birth weights. Head size is associated generally with higher IQ and higher achievements in math and reading in this age group, and in the full IHDP sample head size was associated with improved cognitive function.
The authors can only speculate about explanations for the results of this study, as they had no means of measuring causality between the intervention and the outcomes noted. However, their posited hypotheses include that the intervention might have decreased family stress, which can contribute to growth of children, and also increased overall quality of life for the intervention children.