County-level jail incarceration and preterm birth among non-Hispanic Black and white U.S. women, 1999-2015.

Jail incarceration is widely prevalent in the United States, with disproportionate impacts on communities of color, yet little research has quantified its health consequences for communities. We assess county-level jail incarceration as a contextual stressor for individual-level preterm birth among non-Hispanic Black and White U.S. women, the vast majority (>99%) of whom were not incarcerated, between 1999 and 2015. We linked county jail incarceration rates to birth certificate data for all births to resident non-Hispanic Black and White U.S. women (N = 41, 911, 094). Using multilevel logistic regression models, we estimated the association between quintiles of county jail incarceration rates and the odds of preterm birth, adjusting for maternal- and county-level covariates and state fixed effects. Women living in counties in the highest quintile of jail incarceration rates had 1.08 (95% Confidence Interval (CI): 1.07-1.09) times greater odds of preterm birth, adjusting for covariates, compared to women living in counties with the lowest quintile of jail incarceration rates. Taken together with other research, these findings suggest policies to lower jail incarceration rates could potentially help prevent preterm birth and other adverse population health consequences of mass incarceration.