Abstract Body: The frequency of women undergoing pregnancy at advanced maternal age (AMA, ≥35 years) is increasing in developed countries, including the United States. AMA is associated with an increased risk of adverse pregnancy outcomes such as gestational hypertension, preeclampsia, and preterm birth. Increased risk for adverse pregnancy outcomes at AMA may be mediated in part by altered arterial structure and function or inadequate maternal arterial adaptations during pregnancy. Therefore, we examined central artery stiffness and endothelial function across healthy pregnancy (i.e. no comorbid maternal or fetal conditions, born at term) in women who had enrolled in a longitudinal study between March 2015 and January 2020. We hypothesized that women at AMA (age ≥35 years, mean±SE: 36±0 years, n=18) would have higher arterial stiffness and lower endothelial function compared with younger women (age 21-30 years, mean±SE: 27±0 years, n=51) across pregnancy. Hemodynamic and arterial function measures were collected in the first (6-13 weeks), second (18-26 weeks), and third (27-37 weeks) trimesters and postpartum (4-14 weeks after the delivery). Brachial artery blood pressure was assessed in the supine position and central artery stiffness was assessed via carotid-femoral (aortic) pulse wave velocity (cfPWV) and carotid β-stiffness index. Endothelial function was determined via brachial artery flow-mediated dilation (FMD). Brachial artery systolic, diastolic, and mean blood pressures were not different between AMA and younger women across pregnancy or postpartum (all P>0.05). The AMA group had higher cfPWV (P<0.01) and carotid β-stiffness index (P<0.01) across pregnancy and postpartum compared to the younger group. cfPWV decreased among younger women at the second and third trimesters compared with the first trimester (P<0.01), while cfPWV among women of AMA did not change (P=0.07). There were no differences in FMD between AMA and younger women across pregnancy or postpartum (P=0.96). These results demonstrate that healthy women of AMA have increased central artery stiffness, but no difference in endothelial function, compared to younger pregnant women across pregnancy, and that the normal decrease in aortic stiffness is blunted in pregnant women of AMA compared to younger women. The sustained higher central artery stiffness throughout pregnancy among women of AMA may contribute to increased risk of pregnancy complications and future CVD risk in these women.