Abstract P290: Low and High Birth Weight in Relationship to BMI and Risk of Obesity as Adult in U.S. Black Women
Background: Obesity occurs disproportionately among African-American (AA) women. Although a westernized life-style (e.g. low physical activity and high energy diet) is a major contributor to the obesity epidemic, the higher incidence of obesity in AA women is not fully explained by behavioral factors. Growing evidence indicates that events in the perinatal period may have long-term effects on an individual’s metabolism. In particular, extremes of the birth weight distribution may alter programming of the neuroendocrine system. We postulate that both low and high birth weights result in greater weight gain and obesity risk in adulthood.
Methods: We assessed the association of birth weight with adult body mass index (BMI) and risk of obesity (BMI ≥ 30) in the Black Women’s Health Study (BWHS), an ongoing prospective cohort study that began in 1995 (baseline). We used general linear regression models to estimate mean BMI (baseline) across categories of birth weight (very low birth weight (≤1500 g), low birth weight (1500-2499 g), normal birth weight (2500-3999 g; referent), high birth weight (4000+ g)). We also estimated risk ratios (RR) for obesity (baseline) using log-binomial regression models. Models were adjusted for age at baseline, parental education, maternal age at birth, and energy intake at baseline. The present analyses included 24,089 women who reported their birth weights on a self-administered questionnaire in 1997. We validated self-reported birth weight for the subset of BWHS participants from Massachusetts using birth registry data from the Massachusetts Department of Public Health. Pearson correlation coefficient between self-reported birth weight and registry data was 0.88 and there were no significant differences across BMI categories.
Results: At baseline, mean BMI (±SE, standard error) was 28.0 ± 0.03, and about 28% of the participants were obese. Approximately 2.5% had very low birth weight, 24.3% had low birth weight, 65.2% had normal birth weight, and 8.1% had high birth weight. In multivariate analyses, mean BMI was 0.40 units higher among women with very low birth weight relative to women with normal birth weight (95% CI = -0.08, 0.88); mean BMI was 1.07 units higher among women with high birth weight (95% CI = 0.79, 1.35). Women with very low birth weight had 9% higher risk of obesity (RR = 1.09, 95% CI = 0.97, 1.23) relative to women with normal birth weight; women with high birth weight had 22% higher risk of obesity (RR = 1.22, 95% CI = 1.15, 1.30).
Conclusions: Women with very low or high birth weight had higher mean BMI and greater obesity risk as adults compared with women of normal birth weight. Our results suggest that extremes of the birth weight distribution may inversely affect metabolism over the long-term. Further study is needed to assess the extent to which birth weight explains the higher incidence of obesity in black women.
- © 2013 by American Heart Association, Inc.