Objective: To investigate the effect of childhood weight and childhood socioeconomic status on the pattern of change in body mass index (BMI) between 20 and 43 years.
Methods: A British birth cohort study where the survey members have been followed up regularly since their birth in 1946, with the most recent of 19 follow-ups when the cohort were aged 43 years. BMI was available at 20, 26, 36 and 43 years of age and thus multilevel models for repeated outcome measures were used to model the patterns of change in BMI.
Results: The rate of increase in BMI with age was non-linear, with the rate of increase in mean BMI accelerating with increasing age at different rates for men and women. The mean BMI for men was higher than that for women at all ages. Childhood manual social class, defined in terms of father's occupation, and high relative weight at 14 years of age were associated with higher mean BMI across adult life, and these effects increased with age. The effects of childhood relative weight and social class were independent of educational attainment and adult social class.
Conclusion: The study provides evidence of a long-term effect of childhood social and biological circumstances on BMI. The pathways underlying these relationships may be social or biological, but are not yet fully understood.