Women's health disparities in birth outcomes: A test of the Weathering Hypothesis

Low birthweight (LBW) and preterm births (PTB) are two times higher for African-Americans (AAs) than European-Americans (EAs). The Weathering Hypothesis is a promising model for understanding disparities, but mechanisms of action are rarely tested. We tested whether preexisting and pregnancy-related health conditions may explain the different weathering patterns between races. Methods: Birth records were linked to outpatient billing files and hospital discharge data for all live births of South Carolina Medicaid and health plan recipients from 2004-2006 for the index pregnancy and two years before the pregnancy. We further restricted to AA and EA women with ≥18 months coverage for the period (N=46,087). Health conditions included hypertension and diabetes identified from billing files. Race- and age-stratified logistic regression models were run. Results: The prevalence of hypertension was higher among AAs than EAs starting from 20-24 years old; gaps increased with age. Hypertension was related to both LBW and PTB for all women; diabetes was not. AAs were more likely than EAs to have LBW and prematurity, with gaps widening as women aged. For example, among women 35 or older, without considering hypertension, AA women had higher odds of LBW (OR=2.7) and PTB (OR=1.8) than EAs. Adding hypertension in the model, each of these ORs was reduced by about 10%, indicating that hypertension is a possible mediator. Path analysis will be used to check this mediation. Conclusions: Strategies to reduce racial disparities in birth outcomes should consider physical deterioration during the reproductive years, which could close the gaps in birth outcomes.