This randomized, single-center, nonblind, noninferiority clinical trial is being conducted at a high-risk maternity hospital in southeast Brazil. Eighty postpartum women diagnosed with preeclampsia and requiring magnesium sulfate are randomized into two groups: a 24-hour infusion group (control) and a 12-hour infusion group (intervention). Both groups receive magnesium sulfate via the Zuspan regimen. The primary outcome is the need for additional magnesium sulfate therapy postpartum. Secondary outcomes include maternal complications (e.g., eclampsia, HELLP syndrome), duration of hospitalization, cost-effectiveness, and patient satisfaction. Data are collected over 10 days postpartum and analyzed using descriptive and inferential statistics, with p-values <0.05 considered statistically significant. Ethical approval was obtained, and patient autonomy and data confidentiality are strictly maintained. Os dados não podem ser disponibilizados no momento por se tratar de um estudo em andamento.