Preterm and Early-Term Birth Rates in the US Increased Since 2014

On January 31, 2024, the United States CDC published a National Vital Statistics Report (NVSS) evaluating the distribution of births by gestational age from 2014 to 2022. Through data stratification, the CDC assessed national changes in birth rates across varying patient populations.

The assessment used data from all birth certificates for singleton births registered in the US from 2014 to 2022. Gestational age was divided into multiple categories, including early preterm at under 34 weeks, late-preterm at 34–36 weeks, early-term at 37–38 weeks, full-term at 39–40 weeks, and late- or post-term birth, which includes gestational ages of 41 weeks or longer.

In 2014, the global portion of all preterm births was 7.74%; however, that proportion increased by 12%, reaching 8.67% in 2022. The year-over-year increase was an average of 2% until 2019, with minor fluctuations in 2020, 2021, and 2022.

Beyond preterm births, the rate of early and late preterm births increased simultaneously. More specifically, the rate of early preterm births increased from 2.07% to 2.16% between 2014 and 2022. Comparatively, the rate of late preterm birth increased from 5.67% to 6.51% in that time.

Looking at birth rates based on maternal race and Hispanic origin, the CDC found that across Black, White, and Hispanic mothers, the rate of preterm birth increased. For Black and White mothers, the increase was roughly 11%. However, for Hispanic mothers, the increase was more significant at 13%.

Early- and late-preterm birth was seen across all three races. For example, early-preterm births rose by 2% for Black mothers, 3% for White mothers, and 5% for Hispanic mothers. Comparatively, the rates increased 13–16% for late-preterm births.

Understanding the rates of preterm birth is critical when studying maternal and infant mortality because infants born preterm are at the greatest risk of morbidity and mortality.