Research suggests increasing labor induction prior to 39 weeks

Rates of labor induction in the United States have risen steadily over the past decade, and new national data suggest that this growth has extended beyond the gestational age supported by randomized trial evidence. A research letter published January 28, 2026, in the American Journal of Obstetrics & Gynecology, analyzed United States natality data from 2016 to 2024 and found that non–medically indicated labor induction increased across all gestational ages, with the most pronounced and sustained growth occurring at 37 and 38 weeks’ gestation.¹

The researchers conducted a retrospective analysis using United States Natality Data from 2016 through 2024, spanning periods before and after dissemination of the 39-week induction trial (ARRIVE). To reduce confounding from medical indications, the analysis excluded pregnancies involving prior cesarean delivery, chronic or gestational hypertension, pregestational or gestational diabetes, multiple gestation, and non-vertex presentation.

Gestational age was grouped as 32 weeks or younger, individual weeks from 33 through 41 weeks, and at least 42 weeks. Induction rates were calculated as the proportion of births induced at each gestational week and year. To compare relative growth across gestational ages, proportional changes were indexed to 2016 levels. Temporal trends were assessed using linear regression, and changes between 2016 and 2024 were evaluated using chi-square tests with risk ratios and 95% confidence intervals.

Increase of labor induction rates by gestational age

From 2016 to 2024, induction rates increased at all gestational ages examined, the investigators found. The largest absolute and proportional increases occurred in early-term and term gestations, contributing to a sustained rise in the overall induction rate and a shift toward earlier-term delivery.

“When indexed to 2016, relative growth was heterogeneous by gestational age, with the greatest proportional expansion at 37 and 38 weeks; at these gestations, the annual increase in induction rates accelerated from 1.15% (2016–2018) to 1.59% (2019–2021), with sustained growth of 1.19% annually through 2024, despite attenuation at later gestations,” the authors wrote.

Are earlier labor inductions supported by data?

Randomized trial evidence supporting the benefits of non–medically indicated induction is limited to 39 weeks’ gestation and beyond. The authors conclude that the observed expansion of inductions into earlier gestational ages is aligned with “normalization of deviance,” in which repeated acceptance of an intervention gradually erodes adherence to its original evidentiary limits.

The highly linear growth at 37 and 38 weeks, with R² values exceeding 0.99, suggested that practices initially considered exceptional have become routine despite the absence of supporting evidence. Because natality data lack detailed clinical information, the findings are described as suggestive rather than definitive regarding the appropriateness of these inductions. However, the sustained acceleration through 2024 indicates that the trend is unlikely to be explained solely by temporary changes during the COVID-19 pandemic.

How do these data play a role?

“These findings provide an empirical basis to re-examine current induction practices sanctioning inductions without medical or obstetric indications at 39 weeks’ gestation,” concluded the authors, who also “caution against extending 39-week induction in the absence of a documented medical or obstetric indication to earlier gestational ages.”

Reference:

Grünebaum A, Chervenak FA. Expansion of labor induction beyond 39 weeks into early-term and preterm gestations in the United States, 2016-2024. American Journal of Obstetrics & Gynecology. Research letter. Published January 28, 2026. Accessed January 29, 2026.