Magnesium Sulfate for Seizure Prevention During Pregnancy
Magnesium sulfate is used to prevent or stop seizures
(eclampsia) during pregnancy. It is usually given
through a vein (intravenously, or IV) or injected into a muscle
(intramuscularly, or IM). Treatment to prevent seizures is usually continued
for 24 hours after delivery.
Getting magnesium sulfate through a
vein (IV) is less painful than through IM injection because the IM injections must be
given frequently. The IM delivery route may be used when:
- A pump for adjustable and reliable IV delivery
is not available.
- Continuous monitoring of the health of the mother
and fetus is not possible.
- The mother must be transferred to
another location for treatment.
How It Works
It is not known exactly how magnesium prevents or stops seizures during pregnancy. But it may work by blocking or reducing activity in certain areas of the brain.
Why It Is Used
Magnesium sulfate is used to:
- Prevent seizures in a woman with moderate to
severe preeclampsia. When magnesium sulfate is used
during labor and delivery, it is usually continued for at least 24 hours after
- Stop seizures when they are occurring.
How Well It Works
Magnesium sulfate is effective in reducing the risk of seizures in women who have severe preeclampsia.1 It also prevents repeat seizures in women who have eclampsia.1
Common side effects of this medicine include:
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
In rare cases, symptoms of
magnesium toxicity (nausea, muscle weakness, loss of reflexes) occur during
magnesium sulfate treatment. The medicine calcium gluconate is given to treat
- Affects the central nervous system (brain and
spinal cord) of the mother. Part of normal care when intravenous magnesium
sulfate is given includes checking the mother's reflexes. If too much magnesium
sulfate is given, the mother's reflexes will be slowed. Reflexes are usually
checked about every 2 to 4 hours while the mother is on this
- Affects the fetus's central nervous system. If this
medicine has been given to the mother in large doses and the baby is born
before the drug has had time to clear the mother's body, the baby may have
temporary problems with breathing right after birth. These problems are quickly
reversed with medicine.
- Leaves the mother's body in her urine. The
amount of urine she produces is closely monitored to ensure that this medicine
does not build up in her bloodstream.
Mothers on magnesium sulfate are closely monitored. Blood
pressure and pulse are checked about every 30 minutes for at least the first
few hours of treatment.
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Duley L (2011). Pre-eclampsia, eclampsia, and hypertension; search date February 2010. Online version of BMJ Clinical Evidence: http://www.clinicalevidence.com.
Primary Medical Reviewer
||Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer
||William Gilbert, MD - Maternal and Fetal Medicine
Current as of
||November 5, 2012