Background: The optimal duration of magnesium administration postpartum for prevention of eclampsia has not yet been established. Objective: To investigate the effect of early discontinuation of postpartum magnesium on the rates of postpartum eclampsia when compared to continuation for 24-hour postpartum. Search Strategy: Searches were performed using keywords related to “preeclampsia” and “magnesium sulfate” from inception of database until March 2019. Selection Criteria: Randomized controlled trials of women with preeclampsia receiving magnesium prior to delivery randomized to early discontinuation of magnesium postpartum. The control group was 24-hours of magnesium postpartum. Data Collection and Analysis: The primary outcome was the rate of postpartum eclampsia. Main Results: Eight RCTs with 2,183 women were included with five different magnesium administration time-frames. Eclampsia rates were not different between the two groups (5/1,088 (0.5%) after early discontinuation, versus 2/1,095 (0.2%) in the 24-hour group; RR 2.25, 95% CI 0.5-9.9, I2=0%, 8 studies, 2,183 participants). A number needed to treat was calculated; 370 women would need to receive 24-hours of magnesium postpartum to prevent one episode of postpartum eclampsia. The early discontinuation group had a significant decrease in time to ambulation and breastfeeding. Conclusions: Compared to continuation of magnesium for 24 hours postpartum, early magnesium discontinuation postpartum does not significantly increase the rate of postpartum eclampsia. The largest proportion of women did not receive magnesium postpartum after receiving at least 8 grams intrapartum, thus it is reasonable to consider discontinuation of magnesium postpartum if a woman has received similar adequate dose prior to delivery.