There is growing evidence that maternal health and behaviors in pregnancy, such as pre-pregnancy obesity, excessive gestational weight gain, poor diet, smoking, and adverse pregnancy outcomes, are linked to fetal programming for obesity and cardiovascular disease (CVD) risk in the offspring. Yet, there is a surprising lack of research on the role of prenatal sedentary behavior, physical activity, and sleep (conceptualized together as 24-hour behavior) on offspring obesity risk and CVD risk; this is an unfortunate research gap since there is strong physiological rationale that these behaviors in pregnancy could influence offspring health and are modifiable intervention targets in pregnancy. This multi-site observational cohort study will leverage state-of-the-art, 24-hour behavior assessment in each trimester of pregnancy, collected as part of the Pregnancy 24/7 cohort study and add additional assessments of offspring growth, adiposity, and CVD risk through 24 months to inform future primordial prevention interventions to decrease the risk of offspring obesity and CVD across the lifespan.