Rapid cardiovascular and autonomic adaptations occur during early pregnancy to accommodate augmented cardiac output and placental circulation, with inadequate adaptation associated with hypertensive pregnancy complications. Habitual physical activity (PA) and limiting time in sedentary behaviors (SED) may improve pregnancy-related vascular and autonomic function. The objective of this study was to examine the magnitude of the predicted associations between device-measured PA and SED with cardiovascular and autonomic biomarkers including aortic stiffness, blood pressure variability (BPV) and baroreflex sensitivity (BRS) in the first trimester of pregnancy. Pregnant women (N=92, 21-44 years of age) free from cardiovascular disease were assessed between 10