Allostatic load may not be associated with chronic stress in pregnant women, NHANES 1999–2006

Abstract

PurposePregnant women are generally excluded from studies that measure allostatic load (AL) because there is concern that the changing levels of AL-related biomarkers during pregnancy do not reflect a woman's true AL. The goal of this study was to determine whether AL can be measured in a meaningful way during pregnancy. MethodsThe National Health and Nutrition Examination Survey (NHANES) is a nationally representative, cross-sectional survey of the U.S. civilian population. AL was based on the distributions of 10 biomarkers in pregnant (n = 1138) and nonpregnant (n = 4993) women aged 15 to 44 from NHANES (1999–2006). ResultsThe distribution of each AL-related biomarker differed significantly between pregnant and nonpregnant women (P < .01). Among nonpregnant women, high AL findings were consistent with previous studies (e.g., higher AL in women who are black, are older, and who have lower incomes). However, these associations were not seen in pregnant women. ConclusionsOur results suggest that the various biomarkers that comprise AL may reflect proximal factors in pregnancy more strongly than they represent exposure to chronic stress over a woman's lifetime. Therefore, our approach to measuring AL may not provide meaningful information about chronic stress in pregnant women without further consideration of pregnancy-related factors.