There are huge doubts as to how long to keep postpartum magnesium sulfate. Studies demonstrating the usefulness for 24, 12 or 6 hours are of little evidence and do not take into account the use of magnesium sulphate before delivery. Termination of pregnancy is the best option to prevent eclampsia and magnesium sulphate has proven effective, but do not know the minimum effective dose.The investigators believe that if the patient has received less than 8 continuous hours of magnesium sulphate before delivery, maintain magnesium sulfate for 6 hours is as effective as keeping it for 24 hours.

The definitive treatment known for pre-eclampsia is the interruption of pregnancy. While the definitive treatment is the pregnancy interruption, management includes other measures that have proven effective, including the administration of antihypertensive drugs for severe hypertension and that the use of anticonvulsant such as the magnesium sulfate.

There are multiple studies that prove the effectiveness of magnesium sulfate to prevent eclampsia in patients with severe / serious disorder. Unfortunately these studies used the drug before birth and continue after birth. Therefore the investigators can not conclude whether the administration just before pregnancy is sufficient to prevent seizure. That is, if the cure or definitive treatment of pre-eclampsia is the interruption, did not seem necessary to justify the administration of anticonvulsant drugs after birth. Obvious post delivery management sulfate arises from the large number of postpartum eclampsia reported in many studies. It is unknown if the administration of magnesium sulfate for a minimum period not yet determined before birth and delivery requires even keep the drug after discontinuation.

For all these reasons the investigators propose the following: A randomized trial where all those patients who received magnesium sulfate for less that 8 hours before birth will be randomized to two groups of study: 1- Continue magnesium sulfate for 24 hours and 2-Continue magnesium sulfate for 6 hours postpartum.

Inclusion Criteria:

Severe hypertensive disorder receiving magnesium sulfate prophylaxis for less than 8 hours at birth.

Exclusion Criteria:

• Complications such as: HELLP syndrome, renal failure, eclampsia, retinal detachment, cerebral edema, pulmonary edema, hypertensive encephalopathy.