Background: Eclampsia, the occurrence of a convulsion (fit) in association with pre-eclampsia, remains a rare but serious complication of pregnancy. A number of different anticonvulsants are used to control eclamptic fits and to prevent further convulsions.

Objectives: The objective of this review was to assess the effects of magnesium sulphate compared with phenytoin when used for the care of women with eclampsia. Magnesium sulphate is compared with diazepam and with lytic cocktail in other Cochrane reviews.

Search strategy: We searched the Cochrane Pregnancy and Childbirth trials register (28 November 2002) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2002).

Selection criteria: Randomised trials comparing magnesium sulphate (intravenous or intramuscular administration) with phenytoin for women with a clinical diagnosis of eclampsia.

Data collection and analysis: Both reviewers assessed trial quality and extracted data.

Main results: Six trials involving 897 women are included. Most of the data are from trials of good quality. Magnesium sulphate is associated with a substantial reduction in the recurrence of convulsions, when compared to phenytoin (five trials, 895 women; relative risk (RR) 0.31, 95% confidence interval (CI) 0.20 to 0.47). The trend in maternal mortality favours magnesium sulphate, but this difference is not statistically significant (two trials, 797 women; RR 0.50, 95% CI 0.24 to 1.05). There are also reductions in the risk of pneumonia (RR 0.44, 95% CI 0.24 to 0.79), ventilation (RR 0.66, 95% CI 0.49 to 0.90) and admission to an intensive care unit (RR 0.67, 95% CI 0.50 to 0.89) associated with the use of magnesium sulphate. For the baby, magnesium sulphate was associated with fewer admissions to a special care baby unit (SCBU) (one trial, 518 babies; RR 0.73, 95% CI 0.58 to 0.91) and fewer babies who died or were in SCBU for more than seven days (one trial, 665 babies; RR 0.77, 95% CI 0.63 to 0.95).

Reviewer's conclusions: Magnesium sulphate appears to be substantially more effective than phenytoin for treatment of eclampsia.