Shifts in the Distribution of Births by Gestational Age: United States, 2014-2022.

Objectives-This report presents changes in the distribution of singleton births by gestational age in the United States for 2014-2022, by maternal age and race and Hispanic origin. Methods-Data are based on all birth certificates for singleton births registered in the United States from 2014 to 2022. Gestational age is measured in completed weeks using the obstetric estimate and categorized as early preterm (less than 34 weeks), late preterm (34-36 weeks), total preterm (less than 37 weeks), early term (37-38 weeks), full term (39-40 weeks), and late- and post-term (41 and later weeks). Data are shown by maternal age and race and Hispanic origin. Single weeks of gestation at term (37-41 weeks) are also examined. Results-Despite some fluctuation in most gestational age categories during the pandemic years of 2020-2022, trends from 2014 to 2022 demonstrate a shift towards shorter gestational ages. Preterm and early-term birth rates rose from 2014 to 2022 (by 12% and 20%, respectively), while full-term and lateand post-term births declined (by 6% and 28%, respectively). Similar shifts for each gestational age category were seen across maternal age and race and Hispanic-origin groups. By single week of gestation at term, the largest change was for births at 37 weeks (an increase of 42%).