After recommendation because of the impossibility to end study with 1 center only. Outcomes of patients already included will be evaluated.

Eclampsia is an obstetric emergency capable of prophylaxis. To prevent and control seizures, there is no doubt that the magnesium sulfate (MgSO4) is the ideal drug. However, there are still questions regarding its use and dose. The scheme and the optimal time of administration remain to be elucidated. The objective of this trial is to compare the effectiveness and safety of intravenous magnesium sulfate in the maintenance phase 1g / h versus 2 g / h to prevent eclampsia in pregnant and postpartum women with severe preeclampsia (pure or superimposed).

Hypertensive disorders are frequent during the course of pregnancy-puerperal cycle and an important cause of maternal morbidity and mortality, fetal and perinatal. The high frequency of maternal death can be explained by the presence of numerous complications such as eclampsia. Eclampsia is an obstetric emergency capable of prophylaxis. To prevent and control seizures, there is no doubt that the magnesium sulfate (MgSO4) is the ideal drug. However, there are still questions regarding its use and dose. The scheme and the optimal time of administration remain to be elucidated. Currently, allows the use of either 1 g / h to 2 g / h of magnesium sulphate during the maintenance phase to prevent eclamptic convulsions. However, there is no report in the literature of randomized controlled trials comparing different doses of magnesium sulfate in the maintenance phase to prevent eclampsia.

The objective of this study is to compare the effectiveness and safety of intravenous magnesium sulfate in the maintenance phase 1g / h versus 2 g / h to prevent eclampsia in pregnant and postpartum women with severe preeclampsia (pure or superimposed).There will be a trial randomized and triple blind in the Integrative Medicine Institute Prof. Fernando Figueira (IMIP) from March 2015 to April 2017, and will be included 2000 women randomized into two groups: MgSO4 maintenance dose of 1 g / h or 2 g / h. Patients who had eclampsia before loading dose, with use of other medications or illicit drugs that may interfere with maternal hemodynamics or with contraindications to the use of magnesium sulfate will be excluded. The primary endpoint will be the incidence of eclampsia. Other complications such as oliguria, bleeding, recurrence of seizures, disseminated intravascular coagulation, maternal death, presence of side effects related to the use of MgSO, neonatal outcome and other variables will be considered secondary outcomes. Randomization for preventive treatment of eclamptic seizures with MgSO4 1g / h or MgSO4 2g / h will be held according to a table of sequential numbers from one to 2000, using the letters A and B and not knowing its meaning. The analysis will be performed with the groups identified as A or B, breaking the secrecy only after the results obtained and prepared the tables, or by resolution of the External Monitoring Committee.

Inclusion Criteria:

• Severe Preeclampsia (pure and superimposed)

Exclusion Criteria:

• Eclampsia before administration of the loading dose of MgSO4 ;
• Use of other medications or illicit drugs that may interfere with maternal hemodynamics;
• Contraindications to the use of magnesium sulfate: known hypersensitivity to the drug, oliguria with urine output below 25 ml per hour or anuria (urine output absent) and myasthenia gravis.
• Use of mechanical ventilation