Objective: To estimate the optimal duration of postpartum magnesium sulphate to prevent eclampsia.

Data sources: MEDLINE, EMBASE, CINAHL, the Cochrane Database of Systematic Reviews, and ClinicalTrials.gov databases were searched from inception until January 2020 and limited to English-language human randomized controlled trials. Search strategy included the key works "eclampsia," "magnesium sulphate," and "postpartum."

Methods of study selection: Title, abstract, and full-text review was performed using Covidence data-management software. Of the 3,629 articles screened, 10 studies were included in the final review. Studies were included if they compared two different time points of magnesium sulphate postpartum in women with either preeclampsia or eclampsia.

Tabulation, integration and results: Two authors reviewed studies independently. RevMan software was used to calculate risk difference (RD) for categorical outcomes and mean difference for continuous outcomes. Shorter duration of magnesium sulphate (12 hours or less) was not associated with increased risk of eclampsia compared with 24-hour postpartum regimens (RD -0.01, 95% CI -0.02 to 0.01, I2 70%). Studies randomizing women with preeclampsia did not show increased risk of eclampsia with shorter regimens (RD 0, 95% CI -0.01 to 0.01, I2 0%), nor did trials randomizing those with eclampsia (RD -0.04, 95% CI -0.14 to 0.07, I2 87%). Secondary outcomes, including flushing, duration of Foley catheter insertion, time to ambulation, and duration of hospital stay, were all reduced with shorter-duration magnesium sulphate.

Conclusion: This systematic review and meta-analysis suggests that a shorter duration of postpartum magnesium sulphate does not increase the risk for eclamptic seizure; however, data remain underpowered to render firm conclusions.

Systematic review registration: PROSPERO, CRD42020182432.