Non-Hispanic Black individuals have a significantly higher rate of pre-term births than non-Hispanic white individuals, reports a new Northwestern Medicine study.

In 2019, nearly 12% of non-Hispanic Black individuals experienced preterm births compared with 7% of non-Hispanic white individuals.

This is important because this represents a large number of individuals who are being born early every year that have much higher risk for bad health outcomes and is significantly different between non-Hispanic Black and white individuals.”

Dr. Sadiya Khan, corresponding author, assistant professor of medicine in cardiology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine cardiologist

The study found that pre-pregnancy cardiovascular health explained 8% of the racial difference while social determinants of health explained 20% of the racial difference between Black and white pregnant individuals.

This is the first study that helps explain which of the individual-level maternal health factors (obesity, diabetes, hypertension) and socioeconomic factors (insurance, prenatal care, education) can be targeted to improve birth outcomes and how much each contributes to differences in preterm birth.

“Differences that occur when someone is born early can have important implications not just for the first year of life, but also throughout their life,” Khan said. “Being born early is linked to a higher risk of having heart disease and affects neurodevelopment.”

The study will be published Aug. 7 in the American Journal of Preventive Medicine.

The study included more than 2 million individuals who identified as non-Hispanic white and non-Hispanic Black who had a live birth in 2019. It also utilized data from birth registration records from the National Center for Health Statistics, which collects data on all live births.

“Pre-term birth is the starting point for racial differences across the life course, not just in childhood,” Khan said.

One big problem, she said, is the loss of Medicaid for millions of people in the last three months.

“If you don’t have health insurance when you become pregnant, you are much less likely to get prenatal or cardiovascular care,” Khan said. “Prenatal care in the first trimester is critical to improving birth outcomes.”

Khan said two-thirds of the differences causing pre-term birth weren’t explained by the factors they identified in the study.

“We need to understand the problem so we can fix it,” Khan said. “Understanding racial differences in preterm birth is critical to identifying opportunities for prevention and awareness.”

Other Northwestern authors are Dr. Priya Mehta, Dr. Natalie Cameron, Dr. Priya Freaney, Dr. Amanda Perak, Dr. Nilay Shah, Dr. William Grobman, Dr. Philip Greenland and Kiarri Kershaw.

The paper is titled: “Association of Pre-pregnancy Risk Factors with Racial Differences in Preterm Birth Rates.”

The research was funded by grant HL161514 from the National Heart, Lung, and Blood Institute of the National Institutes of Health.