Short Adult Stature and Overweight Are Associated with Poor Intellectual Performance in Subjects Born Preterm

Abstract

Background/Aims: To study the association between preterm birth and adult intellectual performance, with special emphasis on the influence of postnatal growth. Methods: A population-based cohort study was performed on 272,046 males, born between 1973 and 1978, of whom 248,447 were conscripted for military service between 1991 and 1997. Birth characteristics were obtained from the Swedish Medical Birth Register and information on intellectual performance, final height and BMI were taken from the Swedish Conscript Register. Multiple logistic regression analysis was performed. Results: At conscription, males born preterm had lower results at tests of intellectual performance compared to those born at term. Short adult stature among these males enhanced the risk of low intellectual performance, as compared to those with normal adult stature. Moreover, a high adult BMI in the males born preterm was associated with an increased risk of subnormal performance as compared to those with normal BMI. Conclusions: Subjects born preterm had poorer intellectual performance than those born at term. Short adult stature or a high BMI was associated with an even higher risk for poor intellectual performance in the subjects born preterm. This indicates the occurrence of common mechanisms underlying growth and cognitive development.