How Do Neighborhood Socioeconomics and Pollution Affect Racial Disparities in Birth Outcomes?

Research shows that zip code is an important determinant of health outcomes, but research has rarely pointed to clear interventions for neighborhood health factors. This study explores how much factors related to the mother, neighborhood socioeconomics, and neighborhood air pollution contribute to Black-white disparities in preterm births in California.

Researchers used three datasets: natality files from the California Department of Health Services on all 1.1 million singleton births in California between 2005 and 2010; indicators on unemployment, education, poverty, and language spoken at home from the 2010 Census; and data from the US Environmental Protection Agency and California Air Resources Board on concentrations of fine particulate matter. The prevalence of preterm birth and very preterm birth were 10.9 percent and 1.2 percent, respectively.

Key findings

• Maternal and neighborhood socioeconomic variables explained a greater proportion of Black-white differences in birth outcomes than did air pollution, but the individual contribution of particulate matter was comparable in magnitude to any single maternal or neighborhood socioeconomic factor.
• The hypothesized predictors explain 39.3 percent of the preterm birth disparity, and the adjusted effect of race on preterm birth was equivalent to a risk increase of 51 additional preterm deliveries per 1,000 live births.
• Maternal factors, such as educational attainment, age at delivery, and enrollment in Medicaid, explain 17.5 percent of the disparity.
• Neighborhood socioeconomic factors, such as the unemployment rate, the poverty rate, English proficiency, and educational attainment, explain 16.1 percent of the disparity.
• Neighborhood air pollution, such as particulate matter and nitrogen dioxide, explain 5.7 percent of the disparity.

Air quality has as big of an effect on preterm birth disparities as more commonly recognized and difficult-to-modify factors, such as maternal age and educational attainment. Because individual interventions may not reduce risks and racial disparities in preterm birth, public health professionals should consider policies that improve air quality to reduce Black-white preterm birth disparities.