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• Posted September 27, 2024

U.S. Preterm Births Are on the Rise

Over the past decade, rates of preterm birth in the United States jumped more than 10%, a new study of more than 5 million births shows.

The rise dovetailed with an increase in some factors that make an early delivery more likely, including rates of diabetes, sexually transmitted infections and mental health conditions, along with a corresponding decline in factors that protect against it.

Meanwhile, racial and economic disparities persist.

"These patterns and changes in risk factors should be setting off alarm bells," said lead study author Laura Jelliffe-Pawlowski, a professor at the NYU Rory Meyers College of Medicine in New York City.

Babies born before the 37th week of pregnancy have a higher risk for illness, intellectual and emotional difficulty and even death. 

Factors that have been linked to an increased risk for premature delivery include expectant mothers using tobacco or having diabetes, high blood pressure or an infection. Longstanding trends linked to years of racism also showed up in the new research.

"We found stark differences in terms of what it looks like to be a Black or Native American pregnant person compared with a white individual who is of middle or higher income," said Jelliffe-Pawlowski, who is also a professor emeritus at the University of California School of Medicine.

For the study, her team looked at more than 5.4 million births -- not including twins or multiples -- in the state of California between 2011 and 2022. 

During that time, preterm births rose from 6.8% in 2011 to 7.5% in 2022, dovetailing with a similar nationwide surge between 2014 and 2022.

While rates grew across nearly all groups, they were highest among Black women with public insurance (11.3%) and lowest among white mothers with private insurance (5.8%). While rates fell slightly among Black women who were privately insured, from 9.1% to 8.8%, they remained higher than rates among white mothers.

Among Native Americans with private insurance, preterm births rose from 6.4% to 9.5%.

Among low-income women, prenatal care and participation in the supplemental nutrition program for women and children called WIC were protective. But, participation across most low-income groups fell over the study period, researchers found.

They said the findings point to the need to improve pregnancy care and promote treatments that address risk factors for preterm birth. They noted that these are often underused, especially by mothers of color.

"We need to do a better job of sharing information with pregnant people about risk factors for preterm birth and interventions that may be able to help them address this risk," Jelliffe-Pawlowski said in a university news release. "Some providers report not wanting to scare or overwhelm pregnant people, but pregnant people tend to report wanting to have this information."

In particular, she said women who have had a preterm birth before or who have high blood pressure should discuss taking a low-dose aspirin during pregnancy. 

The researchers are working to develop a digital platform to help women better understand their risk for preterm birth as well as programs that might help them, with an eye to developing a healthy pregnancy plan with their health care provider.

The findings were published Sept. 27 in the journal JAMA Network Open. 

More information

The World Health Organization has more about preterm birth.

SOURCE: New York University, news release, Sept. 27, 2024