Place, Plate and Pollutants: The Association Between Food Security, Nonpersistent Chemical Exposure and Cardiometabolic Health in Pregnancy.

Abstract

Hypertensive disorders of pregnancy (HDP) are a common class of complications onsetting in mid to late pregnancy associated with substantial short- and long-term maternal cardiometabolic risk. HDP disorders are marked by new or worsening gestational hypertension in pregnancy, an important subclinical marker, together with other clinical features that further complicate subtype etiology. In the US, HDP burden is not uniform, and socially and economically disadvantaged women, may face higher and potentially more severe burden of HDP. Concurrently, pregnancy is a period of increased metabolic demands; adequate food access is fundamental to maintaining cardiometabolic health, whereas reduced food access may lower dietary quality and increase exposure to food-related environmental contaminants and endocrine disruptors, thereby elevating cardiometabolic risk. Indeed, food security as a multidimensional construct, along with food-related nonpersistent chemical exposure (i.e. phthalates), are plausible, socially patterned contributors to pregnancy cardiometabolic health, yet this association is less understood. This dissertation sought to examine three related gaps: (1) whether household food security is associated with urinary phthalate metabolite concentrations in US adults; (2) whether neighborhood food access is associated with blood pressure and HDP in pregnancy; and (3) whether neighborhood food access modifies associations between prenatal phthalate mixtures and pregnancy cardiometabolic outcomes. To address these aims, we drew on two complementary data sources: a nationally representative sample and a regional, pregnancy cohort with detailed clinical data. The first study addressed research gap 1 and used data from the National Health and Nutrition Examination Survey (NHANES) to examine cross-sectional associations between household food security and urinary phthalate metabolite concentrations in over 13,000 adults. We found that reduced food security, particularly very low food security, was associated with higher urinary concentrations of several individual and summed phthalate metabolites including hypothesized food associated metabolites. Stronger associations were observed among females and several racial and ethnic groups. The second and third studies used data from the LIFECODES pregnancy cohort in Boston, MA, which includes geocoded residential addresses to assess neighborhood food access (low-income, low-access (LILA) census tracts residence), clinical blood pressure (BP), HDP, and urinary phthalate metabolites. In the second study, where we addressed research gap 2, LILA tract residence was associated with modestly higher third-trimester blood pressure, particularly among Hispanic participants, while evidence for an association with HDP was suggestive but not statistically significant. The third study addressed research gap 3 by examining whether LILA residence modified associations between urinary phthalate metabolites, clinical BP, and HDP. Among LILA residents, higher levels of several individual phthalate metabolites and phthalate mixtures, including hypothesized food-associated metabolites, were associated with increased risk of HDP, whereas associations were weak or null among non-LILA residents. Collectively, this dissertation advances understanding of how multiple dimensions of food security intersect with phthalate exposure that downstream is linked to adverse pregnancy cardiometabolic health, offering a novel approach to studying the complex etiology of HDP. It also highlights how social conditions can concentrate both environmental and health burdens in particular subgroups, and the value of examining heterogeneity to better identify vulnerable populations and the layered contexts in which chronic risk may arise.