Abstract MP78: Device-Based Assessment of 24-Hour Activity Across Three Trimesters of Pregnancy: The Pregnancy 24/7 Cohort Study

Introduction: The 24-hour activity cycle, including moderate-to-vigorous intensity physical activity (MVPA), light-intensity physical activity (LPA), sedentary behavior (SED), and sleep, is increasingly recognized as critical for health. However, little is known about 24-hour activity during pregnancy. This is an important research gap given that these behaviors are modifiable and individually related to maternal and child cardiovascular health outcomes. The purpose of this study was to characterize 24-hour activity across pregnancy using gold standard, device-based measures and examine differences by trimester. Hypothesis: We hypothesized there would be varying patterns of 24-hour activity across pregnancy trimesters. Methods: The ongoing Pregnancy 24/7 multi-site cohort study was conducted to examine associations of 24-hour activity across pregnancy trimesters with hypertensive disorders of pregnancy and other adverse pregnancy outcomes. Participants were instructed to wear the activPAL3 micro (MVPA, LPA, and SED) and the Actiwatch Spectrum Plus (sleep) concurrently for 24 hours x 7 full days in each trimester of pregnancy and to complete a log denoting non-wear and sleep times. Data sources were integrated using PAL Technologies software and a customized R program and descriptive statistics were calculated for each component of 24-hour activity, including the percentage of participants meeting guidelines (when applicable). Differences across trimesters were examined using nested linear or generalized mixed models. Results: A total of n=474 participants to date (mean age 30.8 years ± 4.3, 15.6% Underrepresented Minority) wore both devices in at least one trimester. Time spent in each behavior significantly differed across trimesters (see Table ). MVPA and sleep were highest in the first trimester, while LPA was highest and SED lowest in the second trimester. The percentage of women meeting MVPA guidelines decreased from 54.8% to 44.2%, while the percentage meeting sleep guidelines (time attempting to sleep) increased from 63.2% to 76.1% across trimesters. Meeting a SED threshold of <10 hours/day did not differ across pregnancy trimesters. Conclusions: Declining levels of MVPA during pregnancy suggest a need for tailored health promotion interventions. It may be more feasible to target other components of 24-hour activity during pregnancy, such as decreasing SED by increasing LPA.