NYC Gazette

Preterm births have risen by over 10 percent in the past decade, with persistent racial and socioeconomic disparities, according to a new study analyzing more than five million births. The study, published in JAMA Network Open, also identified an increase in risk factors for preterm birth such as diabetes, sexually transmitted infections, and mental health conditions.

“Our findings not only show that preterm births are on the rise but provide clues as to why this may be the case,” said Laura Jelliffe-Pawlowski, the study’s lead author and an epidemiologist at NYU Rory Meyers College of Nursing. “Understanding patterns of and factors related to preterm birth is important for informing clinical care and the development of public health programs to address this critical need.”

Babies born before the 37th week of pregnancy face higher risks for illness, intellectual and emotional difficulties, and death. Factors increasing these risks include high blood pressure, diabetes, infection, or smoking among mothers. Black, Native American, Hawaiian, and Pacific Islander expectant mothers are at higher risk due to structural racism.

Jelliffe-Pawlowski's team examined over 5.4 million singleton births from 2011 to 2022 in California. They analyzed changes in preterm birth rates over time and explored patterns within racial/ethnic and socioeconomic groups using health insurance type as a proxy for socioeconomic status.

The researchers found that preterm births increased by 10.6 percent from 2011 to 2022—mirroring a CDC report showing a national increase from 2014 to 2022. Rates varied across different groups; Black mothers with public insurance had the highest rates (11.3 percent), while white mothers with nonpublic insurance had the lowest (5.8 percent). Notably, preterm birth rates decreased slightly among Black mothers with nonpublic insurance but remained significantly higher than those among white mothers.

“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.

The study linked several factors to increased risk for preterm birth: diabetes, high blood pressure, previous preterm birth, fewer than three prenatal care visits, and housing insecurity. Rates of preexisting diabetes, sexually transmitted infections, and mental health conditions more than doubled during the decade studied.

“These patterns and changes in risk factors should be setting off alarm bells,” said Jelliffe-Pawlowski.

Factors protecting against preterm birth among low-income expectant mothers included receiving prenatal care and participating in WIC (the supplemental nutrition program supporting women and children). However, WIC participation declined across most low-income racial/ethnic groups during the period studied.

The researchers emphasized improving pregnancy care and promoting treatments addressing risk factors associated with preterm birth. “We need to do a better job of sharing information with pregnant people about risk factors for preterm birth," said Jelliffe-Pawlowski. "Providers should be having conversations about how taking low-dose aspirin might be helpful... screening for sexually transmitted infections... offering mental health care."

“There is also important work to be done to improve structural issues and respectful care in WIC to increase participation,” added Jelliffe-Pawlowski.

Jelliffe-Pawlowski's team is developing Hello Egg—a digital platform aimed at helping expectant mothers understand their risk for preterm birth and create healthy pregnancy plans with prenatal providers. They plan a large study to assess if using Hello Egg increases knowledge about interventions that could reduce adverse outcomes.

The research was supported by UCSF California Preterm Birth Initiative. Study authors include Audrey Lyndon from NYU Meyers along with collaborators from UCSF; UC San Diego; Stanford University; UCLA Medical Center; CSU Northridge; San Francisco State University; Indiana University Bloomington; University of Alabama at Birmingham; and University of Illinois Urbana-Champaign.