Biomarkers of pre-pregnancy allostatic load and subsequent adverse birth outcomes

Racial disparities in birth outcomes are seemingly intractable. Using person-centered methods and drawing from the life course and Weathering Hypothesis literatures, we used data from the National Longitudinal Study of Adolescent to Adult Health to group non-Hispanic White and non-Hispanic Black women ages 24-34 into latent classes based on pre-pregnancy biomarkers of allostatic load. Stratified analyses yielded four latent classes among non-Hispanic White women, characterized by: 1) high blood pressure, 2) high body mass index and waist circumference, 3) high total cholesterol and triglycerides, and low high-density lipoprotein, and 4) low-risk, and two latent classes among non-Hispanic Black women, characterized by: 1) high body mass index and waist circumference, and moderate-risk blood pressure, hbA1c, and c-reactive protein, and 2) low-risk. Allostatic load class membership and other maternal-and infant-level covariates were then included simultaneously as predictors of three separate dichotomous outcomes: preterm birth, macrosomia, and low birth weight in multilevel logistic regression models. In a separate multilevel linear regression model, the same variables were simultaneously entered to predict continuously measured birthweight. In multilevel, multivariate models, White women in the high-risk body mass index and waist circumference class, as compared to the high-risk blood pressure class, had infants with higher birthweights. Other comparisons were not significant or not of meaningful magnitude. Prioritizing temporality so that allostatic load measurement preceded first birth likely biased the composition of the analytical sample. Additional research is needed to help medical providers and public health practitioners understand the complex biological and social mechanisms underlying inequities in birth outcomes and identify prevention strategies.