Preterm, early-term birth rates up in US since 2014

Key takeaways:

• Preterm and early-term birth rates rose from 2014 to 2022, and full-term and late- and post-term births declined.
• From 2014 to 2022, births at 37 weeks gestation had the largest change with a 42% increase.

From 2014 to 2022, preterm and early-term birth rates rose, and late-term and post-term births declined, with similar rates across maternal age, race and ethnicity groups, gestational age a strong predictor of morbidity and early mortality, CDC researchers reported.

“The rate of preterm birth in the United States rose by more than one-third from 1981 to 2006. This rise prompted concern and a heightened awareness of the morbidities associated with births delivered at 34 to 36 weeks of gestation, or late preterm. ... Late preterm and early-term births declined for several years from 2007 to 2014, but have been on the rise in recent years,” wrote Joyce A. Martin, MPH, and Michelle J.K. Osterman, MHS, epidemiologists at the CDC.

To quantify term birth rates since 2014, the researchers used data from the natality data file from the National Vital Statistics System and identified all birth certificates for singleton births registered in the U.S. from 2014 to 2022. Researchers categorized gestational age as less than 34 weeks (early preterm), 34 to 36 weeks (late preterm), less than 37 weeks (total preterm), 37 to 38 weeks (early term), 39 to 40 weeks (full term) and 41 weeks and later ( late- and post-term). Researchers also evaluated data on maternal age, race and Hispanic origin.

From 2014 to 2022, trends demonstrated a shift toward shorter gestational ages despite some fluctuation in most gestational age categories during the COVID-19 pandemic from 2020 to 2022. Preterm birth rates increased by 12% and early-term births increased by 20% from 2014 to 2022. During this same period, full-term births declined by 6% and late- and post-term births declined by 28%.

Researchers observed similar shifts for each gestational age category across maternal age, race and Hispanic origin groups. In addition, when evaluating single week of gestation at term, researchers noted the largest change among births at 37 weeks, with an increase of 42% from 2014 to 2022.

“This report demonstrates a shift from 2014 through 2022 across gestational age categories, with the largest changes occurring among early-term births — particularly those delivered at 37 weeks — and among late- and post-term births,” the researchers wrote. “Similar shifts were observed across the maternal age and race and Hispanic-origin groups studied.”