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Preterm birth in the context of increasing income inequality

Monday, September 22, 2014 — Poster Session I

12:00 p.m. – 2:00 p.m.

FAES Academic Center



* FARE Award Winner


  • ME Wallace
  • P Mendola
  • Z Chen
  • BS Hwang
  • KL Grantz


Preterm birth is a leading cause of infant morbidity and mortality in the US. Little is known about the contextual effect of income inequality on preterm birth, an issue of increasing concern in the US where the current economic divide is the largest since 1928. We examined changes in inequality over time in relation to the preterm birth rate among singleton deliveries from an electronic medical record-based cohort (n=223,512) conducted in 11 US states and the District of Columbia from 2002-2008. Increasing income inequality was defined as a positive change in state-level Gini index from the year prior to birth. Multi-level models estimated the independent effect of increasing inequality on preterm birth (<37 weeks) controlling for maternal demographics, health behaviors, insurance status, chronic medical conditions, and state-level poverty and unemployment during the year of birth. The preterm birth rate was 12.3% where inequality increased and 10.9% where it did not. After adjustment, increasing inequality remained significantly associated with preterm birth (adjusted odds ratio=1.08; 95% confidence interval=1.04, 1.12). We observed no significant interaction by insurance status suggesting that increasing inequality had a broad effect across the population. Mechanisms by which increasing income inequality impacts preterm delivery risk merit further study.

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