The PREG-HEART protocol establishes a groundbreaking digital platform to track cardiovascular disease across pregnancy in the UK, targeting enrollment of women with heart conditions alongside healthy controls through direct-to-patient online recruitment. The study will link self-reported data with national health records for long-term follow-up and collect biosamples for analysis. This represents a paradigm shift in maternal cardiovascular research, which has historically been hampered by small, selective cohorts from individual medical centers. The platform's patient-driven approach could dramatically expand sample sizes and diversity, potentially revealing new patterns in how congenital heart disease, inherited conditions, and acquired risk factors affect pregnancy outcomes. The study's design to support future clinical trials addresses a critical gap in evidence-based management strategies for pregnant women with heart disease. However, as this is a protocol paper for a preprint study not yet peer-reviewed, the actual implementation and recruitment success remain to be demonstrated. The platform's reliance on self-reported data and digital access may introduce selection biases that could limit generalizability to all pregnant women with cardiovascular conditions.