BACKGROUND: Hypertensive pregnancy disorders are associated with long-term adverse cardiac and vascular remodeling post index pregnancy. The POP-HT trial (Physician Optimised Postpartum Hypertension Treatment) demonstrated that improved puerperal blood pressure control leads to reduced blood pressure and beneficial cardiac remodeling during the first year postpartum. This study describes the impact on postpartum vascular remodeling. METHODS: A prospective, randomized, open-label, blinded end point trial in a single UK hospital where 220 women were assigned 1:1 to intervention (self-management via physician-guided antihypertensive titration) or control (usual postnatal care via primary care doctor±midwife). Eligible participants were ≥18 years, with preeclampsia or gestational hypertension and requiring antihypertensives on discharge. Prespecified secondary vascular outcomes included aortic blood pressure and pulse wave velocity measured by Vicorder at baseline and 9 months postpartum, and additional cardiovascular magnetic resonance measures of aortic distensibility were performed. RESULTS: There were no baseline differences in aortic blood pressure or pulse wave velocity but by 9 months postpartum, aortic diastolic blood pressure was -5.2 mm Hg lower ([95% CI, -8.0 to -2.2]; P<0.001), and pulse wave velocity was -0.71 m/s lower ([95% CI, -1.42 to -0.06]; P=0.048) in the intervention arm compared with the control arm, which corresponded with greater aortic distensibility by 0.78×10-3 mm Hg-1 ([95% CI, 0.01 to 1.55]; P=0.046). CONCLUSIONS: Postpartum blood pressure self-monitoring combined with physician-guided medication titration is associated with reduced central arterial stiffness during the first year after a hypertensive pregnancy, in addition to the previously demonstrated effects on blood pressure and cardiac remodeling. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04273854.