Wearable-derived maternal heart rate variability as a novel digital biomarker of preterm birth

Preterm birth remains a significant medical challenge, with limited, infrequently used screening methods currently available to identify risk. When early warning signs are detected, medical interventions—such as the administration of corticosteroids—can significantly improve neonatal outcomes. This study explores whether wearable technology can serve as a novel, non-invasive tool for tracking maternal physiological changes that might signal the approach of labor.

Researchers analyzed data from 241 pregnant individuals who wore WHOOP straps throughout their pregnancies between March 2021 and 2022. The study used mixed-effect spline models to examine night-time heart rate variability (mHRV) data, comparing two potential predictors: gestational age and time remaining until delivery. By evaluating these models against both term and preterm birth outcomes, the authors assessed which temporal metric better explained observed physiological trends.

The study found that for both term and preterm pregnancies, mHRV trends were significantly more strongly aligned with the time remaining until birth than with the calendar progression of gestational age. This inflecton point—a shift in mHRV trends observed in the weeks leading up to delivery—suggests that wearable devices could act as passive, continuous monitors for pregnancy health. Such tools could help identify individuals at higher risk for preterm birth, facilitating timely clinical evaluation even in areas with limited access to obstetric care.

Because traditional screening tools for preterm birth are rarely utilized or have limited clinical reach, many individuals do not receive interventions until it is too late. By providing a low-burden, continuous method to track health, wearable devices could bridge the gap in maternity care, especially in underserved regions or obstetric deserts, potentially reducing the morbidity and mortality associated with preterm delivery.