Allostatic Load in Women with a History of Low Birth Weight Infants: The National Health and Nutrition Examination Survey

Background: The purpose of our study was to determine whether women of reproductive age with history of low birth weight (LBW) deliveries have higher allostatic load (AL), a measure of the cumulative toll of chronic stress, than those with normal-weight deliveries. Methods: We used data from women ages 17-35 who responded to the National Health and Nutrition Examination Survey (NHANES) reproductive-health questionnaire, 1999-2006. Women reported history of LBW infants and those who were preterm. We classified preterm-LBW and term-LBW as surrogates for preterm birth (PTB) and small for gestational age (SGA), respectively. Normal weight included those without LBW infant history. We utilized nine biomarkers measured in NHANES to determine AL and used linear regression to compare unadjusted and adjusted means. Results: We identified 877 women divided among SGA (2%), PTB (10%), and normal groups (88%). The SGA group had higher unadjusted and adjusted AL scores than did the normal group (2.82 +/- 0.35 vs. 1.92 +/- 0.07, p=0.011); women in the PTB group had higher AL scores than did the referent in adjusted analyses (2.58 +/- 0.21 vs. 1.92 +/- 0.07, p=0.001). Conclusions: Women with history of SGA or PTB had higher AL than did those with normal birth weight outcomes. This suggests a link between adverse pregnancy outcomes, chronic stress, and subclinical disease.