[Magnesium sulfate in obstetrics: current data]

To review the available evidence regarding history, pharmacology, physiology, maternal/fetal side effects, and efficacy of magnesium sulfate in pregnant women.

The literature in Medline was searched from 1966 through April 2003 using the terms "magnesium sulfate," "tocolytic," "preeclampsia," "eclampsia," and "pregnancy." Reviews of bibliographies of retrieved articles provided additional references.

Magnesium sulfate (MgSO4) has long been used for prophylaxis of preterm delivery (tocolytic affect) and eclampsia prophylaxis (neuroprotective effect). Randomized controlled trials and systematic reviews have demonstrated the efficacy of magnesium sulfate in preventing eclampsia in patients with preeclampsia or in patients with eclampsia. Whether magnesium sulfate should be administered to patients with severe preeclampsia or to mild preeclampsia is discussed in the manuscript. Inversely, it appears that magnesium sulfate is ineffective in delaying birth or preventing preterm birth when it is used as a tocolytic. Furthermore, there is evidence that high cumulative doses of magnesium sulfate may be associated with increased infant mortality.

The evidence to date confirms the efficacy of magnesium sulfate therapy for women with eclampsia and preeclampsia. However, magnesium sulfate should not be used in order to treat preterm labor.