Adverse Pregnancy Outcomes and Sedentary Behavior, Light-Intensity Physical Activity, and Daily Steps

Importance: Although moderate- to vigorous-intensity physical activity is recommended to reduce the risk of adverse pregnancy outcomes, associations between lower-intensity activities and adverse pregnancy outcomes are not established. Objective: To determine associations between adverse pregnancy outcomes and sedentary behavior (SED), light-intensity physical activity (LPA), and daily steps. Design, Setting, and Participants: Cohort study conducted from 2021 to 2025, involving 470 pregnant volunteers at less than 13 weeks' gestation at university-affiliated medical centers in Iowa, Pennsylvania, and West Virginia. Statistical analyses were conducted between October 2025 and April 2026. Exposures: Device-based SED, LPA, and daily steps were assessed each trimester, using a thigh-worn accelerometer. Participants were separated into groups based on their activity patterns across pregnancy for SED (total, short SED with