Fetal and early life growth and body mass index from birth to early adulthood in 1958 British cohort: longitudinal study

Objectives To determine the influence of birth weight on body mass index at different stages of later life; whether this relation persists after accou nting for potential confounding factors; and the role of indicators of feta l growth (birth weight relative to parental size) and childhood growth. Design Longitudinal study of the 1958 British birth cohort. Setting England, Scotland, and Wales. Participants All singletons born 3-9 March 1958 (10 683 participants with d ata available at age 33). Main outcome measures Body mass index at ages 7, 11, 16, 23, and 33 years. Results The relation between birth weight and body mass index was positive and weak, becoming more J shaped with increasing age. When adjustments were made for maternal weight, there was no relation between birth weight and b oyd mass index at age 33. Indicators of poor fetal growth based on the moth er's body size were not predictive, but the risk of adult obesity was highe r among participants who had grown to a greater proportion of their eventua l adult height by age 7. In men only, the effect of childhood growth was st rongest in those with lower birth weights and, to a lesser extend, those bo rn to lighter mothers. Conclusions Maternal weight (or body mass index) largely explains the assoc iation between birth weight and adult body mass index, and it may be a more important risk factor for obesity in the child than birth weight. Birth we ight and maternal weight seem to modify the effect of childhood linear grow th on adult obesity in men. Intergenerational associations between the moth er's and her offspring's body mass index seem to underlie the well document ed association between birth weight and body mass index. Other measures of fetal growth are needed for a fuller understanding of the role of the intra uterine environment in the development of obesity.