Long-Term Effects of Birth Weight and Breast-Feeding Duration on Inflammation in Early Adulthood (WP-13-13)
Thomas McDade, Molly Metzger, Laura Chyu, Greg Duncan, Craig Garfield, and Emma Adam
Chronic inflammation is a potentially important physiological mechanism linking social environments and health across the life course. Elevated concentrations of C-reactive protein (CRP)—a key biomarker of inflammation—predict increased cardiovascular and metabolic disease risk in adulthood, but the developmental factors that shape the regulation of inflammation are not known. Lower birth weight and shorter durations of breast-feeding in infancy are potentially important determinants of chronic inflammation. Using data from a large, nationally representative sample of young adults in the United States (National Longitudinal Study of Adolescent Health), the authors estimated a series of weighted least squares regression and fixed-effects sibling comparison models to evaluate birth weight and breast-feeding duration as predictors of CRP in adulthood (24-32 years). Complete data were available for nearly 10,500 participants. Lower birth weight was associated with higher CRP in weighted least squares and sibling comparison models. Breast-feeding duration was considered as a series of indicator variables. Compared with individuals not breast-fed, CRP concentrations were 19.9 percent, 27.3 percent, 29 percent, and 30.9 percent lower among individuals breast-fed for fewer than 3 months, 3-6 months, 6-12 months, and longer than 12 months, respectively. In sibling comparison models, breastfeeding longer than 3 months was marginally associated with lower CRP. Efforts to promote breast-feeding and improve birth outcomes may have clinically relevant effects on reducing levels of chronic inflammation and lowering risk for cardiovascular and metabolic diseases in adulthood. A focus on early environments may also reduce social disparities in these diseases in adulthood, which run parallel to, and perhaps derive in part from, social disparities in birth weight and breast-feeding behavior.