Executive function in 7-9-year-old children born extremely preterm or with extremely low birth weight: effects of biomedical history, age at assessment, and socioeconomic status.

Forty-five children born extremely preterm and/or with extremely low birth weight (ELBW), who were of average intelligence, were assessed at age 7-9 on a raft of measures of executive function (EF) designed to assess inhibition, set shifting, planning, fluency, and working memory. Relative to 45 full-term controls, the preterm/ELBW children showed reliable impairments of inhibition, fluency, and working memory. Among the 7-year olds, the preterm/ELBW group also showed significantly worse set shifting. After controlling for age and family socioeconomic status (SES), within-group analyses of the preterm/ELBW data revealed that higher birth weights were associated with better inhibition, whereas lower neurobiological risk (gauged by such aspects of neonatal medical history as a number of days on oxygen) was associated with better planning. Moreover, there were interactions between neurobiological risk and SES on the measures of inhibition, fluency, and working memory, indicating that the adverse effects of risk were greater among children from low-income households. These findings demonstrate that neonatal medical problems are associated with considerable variability in EF among normally developing preterm/ELBW children and implicate an important influence of the family environment on the maturation of EF.