Background <p><?noindent??>Hypertensive disorders of pregnancy affect around 10% of pregnant women and can continue following childbirth. Such hypertension that persists postnatally can be unpredictable and may have long-term health consequences but care can be sub-optimal with poor support as women transition from maternity to community services. However, there is little evidence to guide best practice for managing postnatal hypertension, and these gaps in evidence and care disproportionately affect women from minoritised ethnic and socioeconomically disadvantaged backgrounds.</p> <p><?noindent??>Previous work suggests self-management where women self-monitor blood pressure (BP) and self-titrate medication, overseen by clinicians, could improve BP control in the short and long term but has been limited to single geographical areas. The aim of the SNAP2 trial is to evaluate the clinical and cost effectiveness of a self-management intervention at scale.</p> Methods <p><?noindent??>SNAP2 is a multi-centre unblinded randomised controlled trial. A planned sample of at least 628 participants across England with any pregnancy hypertension will be randomised within 7 days post birth to a digitally-supported self-management intervention, including self-monitoring of BP and clinician-guided titration of anti-hypertensive medication, or usual care. A cross-cutting theme is evaluating how health equity can best be ensured in postnatal hypertension management.</p> <p><?noindent??>The primary outcome is the difference in mean daytime ambulatory diastolic BP between intervention and usual care, measured between 22 to 39 weeks postpartum. Secondary outcomes include other measures of BP, maternal quality-of-life, medication adherence, adverse outcomes and readmission to hospital up to one year after birth. A qualitative process evaluation will explore how the intervention is implemented and integrated into women’s lives and clinical pathways. An economic analysis will evaluate within-trial cost and outcomes and long-term economic modelling.</p> Discussion <p><?noindent??>The SNAP2 trial will provide essential data on the clinical and cost-effectiveness of a self-management intervention that, if proven effective, could improve current sub-optimal postnatal care for BP management. In-depth qualitative and equity data will provide important insight to inform potential implementation.</p> <p><?noindent??>Throughout the manuscript, in our references to women, we encompass all birthing people.</p> Clinical trail number <p><a href="https://doi.org/10.1186/ISRCTN11042045">https://doi.org/10.1186/ISRCTN11042045</a>.</p>