Is restricted fetal growth associated with later adiposity? Observational analysis of a randomized trial.

BACKGROUND Several recent "developmental origins" studies have reported increased long-term risks of adiposity, especially truncal adiposity, among children born small for gestational age (SGA). OBJECTIVE We assessed the effects of SGA birth and weight gain in early infancy on adiposity at age 11.5 y. DESIGN From a cluster-randomized breastfeeding promotion trial in 17,046 Belarusian children, we measured height, weight, waist and hip circumferences, triceps and subscapular skinfold thicknesses, and bioimpedance measures of percentage body fat at age 11.5 y. Children born SGA (birth weight <10th percentile) and those born large for gestational age (LGA; >90th percentile for gestational age) were compared with those born appropriate for gestational age (AGA). Weight gain from birth to 6 mo was categorized as high (>0.67-SD increase in weight-for-age), low (>0.67-SD decrease in weight-for-age), or normal. Multilevel statistical models accounted for clustered measurement and controlled for maternal and paternal height and body mass index (BMI), maternal education, geographic region, urban compared with rural residence, and the child's exact age at follow-up. RESULTS Children born SGA had a significantly lower BMI, percentage body fat, and fat mass index than did those born AGA, with a dose-response effect across 2 subcategories of SGA (P < 0.001 for all comparisons). No difference was observed in waist-to-hip ratio, although the subscapular-to-triceps skinfold ratio was slightly but significantly (P < 0.001) higher in children born SGA. Differences among the study groups continued to increase since the previous follow-up at 6.5 y. SGA infants with catch-up growth in the first 3-6 mo had growth and adiposity measures intermediate between those born SGA without catch-up and those born AGA. Opposite effects of similar magnitude were observed in children born LGA. CONCLUSION The 11.5-y-old Belarusian children born SGA were shorter, were thinner, and had less body fat than their non-SGA peers, irrespective of postnatal weight gain. The Promotion of Breastfeeding Intervention Trial was registered at www.isrctn.org as ISRCTN-37687716.