Early risk factors for increased adiposity: a cohort study of African American subjects followed from birth to young adulthood

Background: Obesity is an increasing concern in the United States. Effectiv e prevention of obesity requires the risk factors to he well defined. Afric an Americans have a high risk of obesity. Objective: The objective of this study was to identify risk factors, presen t at birth, for increased adiposity in adulthood in an African American pop ulation. Design: In this retrospective analysis of a prospective cohort study, anthr opometric and socioeconomic variables were collected at birth. A representa tive sample of 447 African American subjects was followed up until young ad ulthood, when skinfold thickness was measured. Associations between the ind ependent variables and increased adiposity (skinfold thickness above the 85 th percentile) were explored by using unadjusted and adjusted analyses. Results: Three variables measured at birth were independently associated wi th adiposity in young adulthood, explaining 12% of the variance. The odds r atios (with 95% CIs) of these variables for increased adiposity were 2.7 (1 .2, 6.2) for female sex, 4.0 (1.4, 11.2) for first-born status, and 1.15 (1 .06, 1.25) for each unit increment in maternal prepregnancy body mass index (BMI; in kg/m(2)). After adjustment for these variables, birth weight for gestational age and socioeconomic variables were not associated with adipos ity. Conclusions: This cohort study of African American subjects was the first t o identify first-born status as an independent risk factor for increased ad iposity in adulthood in a US population. The results of the study strengthe n previous reports of the effect of female sex and maternal BMI on adulthoo d obesity. Identification of risk factors early in Life may help target pre vention toward high-risk children and allow healthy lifestyles to be establ ished before the onset of obesity.