Pregnancy Salt Substitution Trial for Hypertensive Disorders of Pregnancy Prevention (PREG-Salt)

The PREG-Salt study is to evaluate the effect, safety and cost-effectiveness of low-sodium salt in reducing blood pressure and preventing hypertensive disorders in pregnant women at high risk in China. The study will recruit about 3,200 participants from approximately 100 hospitals across multiple provinces in China. Eligible pregnant women (≤16 weeks of gestation) will be randomly assigned in a 1:1 ratio to the following 2 groups: 1. Salt subsittute(intervention); 2. Usual salt (control) . The intervention will last until delivery. The study employs an adaptive two-phase design. An interim analysis after the first phase (n=400) will inform whether the trial continues into the second phase and if any adjustments to the sample size are needed. The primary outcomes are: Phase 1: The mean systolic blood pressure across antenatal visits (excluding the last week before delivery). Phase 2: New-onset hypertensive disorders of pregnancy and related adverse events from randomization to delivery.