Early magnesium discontinuation postpartum and eclampsia risk: A systematic review and meta-analysis

The optimal duration of magnesium administration postpartum for prevention of eclampsia has not yet been established. Our objective was to investigate the effect of early discontinuation of postpartum magnesium on the rates of postpartum eclampsia compared to continuation for 24-hours postpartum.

Searches were performed using keywords related to "preeclampsia" and "magnesium sulfate" from inception of database until August 2023. Randomized controlled trials of women with preeclampsia were included if they received magnesium prior to delivery and were randomized to early discontinuation versus 24-hours of magnesium postpartum. The primary outcome was the rate of postpartum eclampsia.

Nine RCTs with 2183 women were included with five different magnesium administration time frames. In total, seven patients with postpartum eclampsia were reported in three studies. Eclampsia rates were not different between the two groups (5/1088 (0.5 %) after early discontinuation, versus 2/1095 (0.2 %) in the 24-hour group; RR 2.25, 95 % CI 0.5-9.9, I² = 0 %, 8 studies, 2183 participants). A number needed to treat was calculated; 374 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 (-9.1 h, 95 % CI -14.7 - (-3.6), I² = 98 %, 3 studies, 1509 participants) and breastfeeding (-8.4 h, 95 % CI -12.0 - (-4.8), I² = 98 %, 2 studies, 1397 participants).

Early magnesium discontinuation postpartum, usually ≤6 h or none at all, did not significantly increase the rate of postpartum eclampsia, however this study is likely underpowered to demonstrate a difference. The number needed to treat is similar to the number needed to treat for antepartum preeclampsia without severe features, for which magnesium is not recommended. The largest proportion of women did not receive magnesium postpartum after receiving at least 8 h of magnesium intrapartum (e.g., loading and maintenance dose). Thus, it is reasonable to consider not using magnesium postpartum, particularly if a woman has received similar adequate dose prior to delivery.