Birth weight; postnatal, infant, and childhood growth; and obesity in young adulthood: evidence from the Barry Caerphilly Growth Study.

BACKGROUND Birth weight has been shown to be positively associated with adult obesity, but relatively few studies have examined the associations with growth in specific periods of early childhood. OBJECTIVE The objective was to assess the association of measures of growth between birth and 5 y of age with adult measures of adiposity. DESIGN We conducted a longitudinal study of young adults from Barry and Caerphilly, United Kingdom, who had previously taken part between 1972 and 1974 in a randomized controlled trial of milk supplementation. We reexamined 679 men and women (72% of the target population) to measure body mass index (BMI; in kg/m(2)), waist-to-hip ratio, sagittal abdominal diameter, and waist circumference. RESULTS An increase in weight velocity from 1 y and 9 mo to 5 y of age was the most important predictor of BMI, waist circumference, and sagittal abdominal diameter. A z-score increase in weight gain in this period was associated with an increase in BMI of 1.13 (95% CI: 0.69, 1.57; P < 0.001). Infant weight gain from 5 mo to 1 y and 9 mo was the strongest predictor of waist-to-hip ratio (0.51; 95% CI: 0.00, 1.02; P = 0.05). CONCLUSIONS Birth weight does not predict adiposity on the basis of weight gain in childhood. The association between adult adiposity and weight gain in different periods is variable and depends on the measure of adiposity that is used. It remains unclear whether early childhood is the optimum period in the life course for the primary prevention of adult adiposity.