Blood loss at cesarean delivery in women on magnesium sulfate for preeclampsia.

Objective: To evaluate the effect of magnesium sulfate for prevention of eclampsia on blood loss at time of cesarean delivery (CD).

Methods: We conducted an electronic based search using the following databases: MEDLINE, PUBMED and the Cochrane Library. The search terms were "magnesium sulfate", "preeclampsia" and "randomized". Inclusion criteria were randomized controlled trials of women with preeclampsia who delivered with or without magnesium sulfate therapy for seizure prophylaxis. Only trials with placebo or no treatment comparison groups were included. Primary outcome was postpartum hemorrhage. Secondary outcomes were estimated blood loss, change in hemoglobin, blood transfusion and eclampsia.

Results: Five trials met inclusion criteria. The incidence of postpartum hemorrhage was similar between the two groups [magnesium sulfate: 754/4482 (17%); no magnesium sulfate: 775/4427 (18%); RR 0.97, 95% CI 0.88-1.06]. There was no statistical difference between any of the other blood loss outcomes reported in the included studies. The rate of eclampsia with magnesium sulfate was significantly lower than with placebo (42/5604, 0.7%, versus 107/5600, 1.9%; RR 0.40, 95% CI 0.28-0.57).

Conclusions: Magnesium sulfate does not appear to affect blood loss intrapartum and postpartum in women with preeclampsia. Magnesium sulfate, therefore, should be continued during CD, given the benefit of seizure prophylaxis without any increased risk of hemorrhage.