Sedentary Behavior and Cardiovascular Health in Young Women - ABSTRACT Women have more rapid cardiovascular disease (CVD) risk development compared to men during young adulthood; yet, little research has studied factors that could curtail CVD risk development during this critical period for young women. The Nulliparous Pregnancy Outcomes Study Monitoring Mothers-to-Be Heart Health Study (nuMoM2b HHS) is a unique, multi-center, longitudinal cohort, originating during the first pregnancy, that is now studying associations between adverse pregnancy outcomes (APO) and modifiable CVD risk in women. This ancillary application to nuMoM2b HHS aims to test our hypotheses that sedentary behavior (SED) is a key, modifiable risk factor for CVD risk development in young women, including those with APO. SED is low-intensity behavior in a seated, reclining, or lying posture and has recently been identified as a CVD risk factor that is distinct from insufficient moderate-to-vigorous intensity activity (MVPA). Acute prolonged sitting results in marked, adverse responses such as increased blood pressure (BP), glucose, and lipids. Yet, major research gaps preclude the development and testing of specific SED-reduction interventions, especially for young women. Most studies measure SED poorly (e.g., by self-report) and do not statistically consider that SED is part of an all-day activity pattern (or composition). Further, mechanisms of how SED leads to CVD are unclear, further limiting intervention development. Last, almost no studies focus on young women. Our preliminary data suggest that SED is strongly associated with APOs and reduced cardiovascular health (e.g., BP) in young women post-pregnancy. Further, our laboratory has recently demonstrated novel associations between SED and mechanistic CVD measures, including greater arterial stiffness (higher pulse wave velocity [PWV]) and worse autonomic function (lower heart rate variability [HRV]). Collectively, SED is a novel, understudied risk factor for reduced cardiovascular health that our data suggest is highly relevant for young women. We have a unique, efficient, and time-sensitive opportunity to address these gaps by adding gold standard SED assessment via activPAL thigh-mounted accelerometer to the upcoming HHS2 exam. In this contemporary and diverse female cohort (n=4,050, age=36±6 years), we aim to quantify cross-sectional and longitudinal associations of SED with the clinical components of idea cardiovascular health (BP, BMI, total cholesterol, fasting glucose) by using state-of-the-art statistical methods that consider the compositional nature of SED and 24-hr activity and can correct existing, longitudinal self-reported SED via regression calibration. Also, we add HRV and PWV in Pittsburgh and Indiana (n=950) to efficiently study associations between SED and subclinical, mechanistic CVD outcomes in young women. Aim 3 will study interrelationships of SED, APO history, and ideal cardiovascular health to identify novel risk reductions strategies in this high-risk group with limited treatment options. This research will provide critical data to rigorously link SED, CVD risk, and contributing mechanisms and will inform age- and sex-specific SED interventions to test in young women, including those with APO.
