School performance and IQ-test scores at age 13 as related to birth weight and gestational age.

The cohort in the present longitudinal research program consisted of 873 children in an entire school grade, in a Swedish community. The present results showed a main effect of birth weight; low birth weight (LBW) children had lower school performance and intelligence-test (IQ) scores at age 13 than did normal birth weight (NBW) children irrespective of parental SES. Second, there was no significant main effect of gestational age (GA) on scholastic performance and IQ-test scores. Third, there was a significant main effect of the combination of birth weight and GA on scholastic performance and IQ-test scores. The LBW children born at term (38-40 pregnancy weeks; pw) had significantly lower scores and school grades as compared to the control group while the LBW children born with short gestational age (34-37 pw) and with very short gestational age (less than 34 pw) had significantly lower scores and marks in fewer areas of academic attainment.