A recent study has revealed that preterm birth rates in the United States increased from 2011 to 2021, particularly among households earning less than 200% of the federal poverty level. The research, conducted by specialists at Boston Medical Center in collaboration with the University of Massachusetts Chan Medical School and the Harvard T.H. Chan School of Public Health, highlights significant disparities linked to race and income.
Preterm birth, defined as delivery before 37 weeks of gestation, is a leading cause of infant mortality and morbidity in the United States. This study is particularly alarming as it underscores systemic inequalities that have persisted over decades. According to earlier research, Black individuals face nearly double the risk of preterm birth compared to their white counterparts, a disparity that remains unchanged.
Understanding the Intersection of Income and Race
The study, titled “Trends in US Preterm Birth Rates by Household Income and Race and Ethnicity,” published in JAMA Network Open, analyzed data from 411,469 mothers and their infants to explore the relationship between household income and preterm birth across different racial and ethnic groups. The categories included American Indian or Alaska Native, Asian, Hispanic, non-Hispanic Black, non-Hispanic white, and multiracial individuals.
Researchers utilized the Pregnancy Risk Assessment Monitoring System (PRAMS), a comprehensive surveillance system developed by the Centers for Disease Control and Prevention (CDC). This system is administered by state health departments and collects postpartum surveys from mothers, linking responses to birth certificate data for additional demographic insights.
Income levels were categorized into three groups: those earning less than 100% of the federal poverty level, those earning between 100% and 199%, and those earning 200% or more. For reference, the federal poverty level for a one-person household was set at $15,650 in 2025, while a three-person household was $26,650.
Trends in Preterm Birth Rates
The findings illustrate a concerning trend: preterm birth rates averaged 10.4% among households earning less than 100% of the federal poverty level, 8.9% among those earning between 100% and 199%, and 7.5% among households earning 200% or more during the decade studied. Notably, the rates for households under 100% of the poverty level rose from 9.7% in 2011 to 11.1% in 2021, reflecting a troubling increase. Similarly, households earning between 100% and 199% saw rates rise from 7.8% to 10.0% during the same period.
Analysis revealed that Black mothers experienced the highest preterm birth rates across all income levels. Comparatively, Black mothers were linked to a 19% higher adjusted relative risk of preterm birth at the lowest income level and a 13% higher risk at the highest income level compared to white mothers. Notably, no significant differences were observed in middle-income groups.
A Call for Comprehensive Solutions
The study concludes that disparities in preterm birth rates based on household income have widened over time. Researchers emphasize the need to delve deeper into the role of systemic racism and racial inequality in these disparities. Public health initiatives aimed at reducing preterm births may be ineffective if they focus solely on income levels without considering the broader socio-economic factors at play.
To effectively address these disparities, the authors recommend interventions that tackle socio-economic factors and structural inequalities impacting Black communities. Strategies could include enhancing access to timely and comprehensive prenatal care, addressing chronic health conditions in mothers, alleviating stress, and combating racial and ethnic discrimination in healthcare.
This study shines a critical light on the intersection of poverty, race, and health outcomes in the United States, reinforcing the need for targeted public health policies to ensure equitable care for all mothers and their infants.
