Life-course socio-economic factors, skin colour and abdominal obesity in adulthood in a Brazilian birth cohort

OBJECTIVE Obesity is an increasingly prevalent nutritional disorder throughout the world. In particular, abdominal obesity is associated with cardiovascular and metabolic risk. The present study aimed to evaluate the effects of skin colour and life-course socio-economic indicators on waist circumference (WC), hip circumference (HC) and waist:hip ratio (WHR) in young adults. DESIGN Population-based birth cohort study. Individuals born in 1982 in Pelotas (southern Brazil) were visited on a number of occasions from birth to age 23-24 years. A sample of the cohort was sought in 2006 and 972 individuals were located. The analysis was restricted to individuals with complete data available (442 males, 414 females). RESULTS In men, family income at birth and in 2004-5 were positively associated with WC and HC, but not with WHR. Regardless of current income, men born to wealthier families had larger WC and HC as adults. Skin colour was not associated with any of the outcomes. In women, early poverty was associated with smaller HC, and current poverty with larger WC. Poverty at any age thus led to higher WHR. Black women had larger WC and HC than white women, but there were no differences in WHR. All the associations were partially mediated by education and behavioural variables. CONCLUSIONS The effects of early socio-economic position on WC and HC persist even after adjustment for adult socio-economic position, highlighting the importance of interventions during the first years of life.