In utero exposure to threat of evictions and preterm birth: evidence from the United States

OBJECTIVE: To estimate county-level associations between in utero exposure to threatened evictions and preterm birth in the United States. DATA SOURCES: Complete birth records were obtained from the National Center for Health Statistics (2009-2016). Threatened evictions were measured at the county level using eviction case filing data obtained from The Eviction Lab (2008-2016). Additional economic and demographic data were obtained from the United States Census Bureau and Bureau of Labor Statistics. STUDY DESIGN: We conducted a retrospective cohort analysis using 7.3 million births from 1,633 counties. We defined threatened eviction exposures as the z-score of average case filings over the pregnancy and by trimester. Our primary outcome was an indicator for preterm birth (born < 37 completed weeks of gestation). Secondary outcomes included a continuous measure for gestational length, a continuous measure for birth weight, and an indicator for low birth weight (born < 2500 g). We estimated within-county associations controlling for individual- and time-varying county-level characteristics, state-of-residence-year-and-month-of-conception fixed effects, and a county-specific time trend. DATA COLLECTION/EXTRACTION: We merged birth records with threatened eviction data at the county-month-year level using mother's county of residence at delivery and month-year of conception. We supplemented these data with information on county-level annual 18-and-over population, annual poverty rate, and monthly unemployment rate. PRINCIPAL FINDINGS: Increased levels of eviction case filings over a pregnancy were associated with an increased risk of prematurity and low birth weight. These associations appeared to be sensitive to exposure in the second and third trimesters. Associations with secondary outcomes and within various population subgroups were, in general, imprecisely estimated. CONCLUSIONS: Higher exposure to eviction case filings within counties, particularly in the latter stages of a pregnancy, was associated with an increased risk of adverse birth outcomes. Future research should identify the causal effect of threatened evictions on maternal and child health outcomes.