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Fewer prenatal visits associated with higher rates of preterm birth

The rate of preterm birth—the second-leading cause of infant mortality in the United States—is highest among Black women compared with women of all other race and ethnicities. This study sought to examine risk and protective factors for preterm birth among Black women in Oakland, California. Having fewer than three prenatal care visits was associated with higher preterm birth rates, as was hypertension, previous preterm birth and unknown participation in the Women, Infant, Children program.

Key Findings

Black women are consistently found to be at highest risk for preterm birth across the United States. These differences persist even when accounting for known individual-level risk factors.
8.7% of the 6,199 women in the study had a preterm birth.
Having fewer than three prenatal visits was associated with the highest level of increased risk for prenatal birth, which emphasizes the importance of exploring local barriers to prenatal care.
Previous preterm birth, hypertension and unknown WIC participation were also risk factors.
By contrast, participation in WIC and maternal birth outside of the United States were associated with lower risk of preterm birth.

Study Design

Researchers used patient data from Black women who gave birth to single babies between 20 and 44 weeks of gestation, from January 1, 2011 through December 31, 2017, and who had a residential address upon giving birth that corresponded to the city of Oakland. Preterm birth was defined as less than 37 weeks’ gestation.

“We speculate that in this study, a number of prenatal care visits may in fact be serving as a proxy for issues of racial discrimination, housing insecurity, or stress. These factors must be directly explored in future studies and the findings translated into actionable interventions.”


No population-based studies to date have examined risk factors for preterm birth among Black women in Oakland. This analysis was intentionally focused on the specific geography of Oakland, and the specific population of Black women within that city. As such, researchers noted that their results may not be generalizable to other populations of Black women. That said, the findings of this study are supported by others showing that Black women are less likely to experience or receive adequate prenatal care, and show the link between hypertension and preterm birth in Black women.

This study, Risk and Protective Factors for Preterm Birth Among Black Women in Oakland, California, was published in the Journal of Racial and Ethnic Health Disparities.