Magnesium sulfate is most commonly used for the treatment
of
preeclampsia during pregnancy. Use of magnesium for
the treatment of
preterm labor or preeclampsia is an
unlabeled use of the medicine.
Magnesium
sulfate is sometimes used as a
tocolytic medicine to slow uterine contractions during
preterm labor. But studies show it does not stop preterm labor and it may cause
complications for both mother and baby.1
Magnesium sulfate is usually given through a vein (intravenously) until contractions have slowed and the
mother's
cervix has stopped thinning (effacing) or opening
(dilating).
Some hospitals use magnesium sulfate
for preterm labor.2 Magnesium sulfate may be used to
stop preterm labor when:
Labor needs to be delayed for 24 to 48 hours
to:
Let
corticosteroids given to the mother help fetal lungs
mature.
Provide time to move a mother to a hospital that offers
neonatal intensive care, if her local hospital does not.
Regular contractions of the uterus have thinned
(effaced) the
cervix and opened (dilated) it less than
4 cm, and the mother's
amniotic sac has not broken.
The mother is
healthy.
The fetus is alive and not in
distress.
Another tocolytic medicine has not slowed uterine
contractions.
Treatment with other tocolytic medicines has been stopped because
of side effects.
Side effects are common with magnesium
sulfate and can affect both the mother and fetus. Side effects of magnesium
sulfate that may affect the mother include:
Muscle weakness.
Lack of
energy.
Low blood pressure
(rare).
Headache.
Nausea and
vomiting.
Stuffy nose.
Chest pain.
Buildup
of fluid in the lungs (pulmonary edema) and slowed or difficult
breathing.
Blurry vision.
Slurred speech.
Flushing.
These side effects can decrease over the duration of
treatment and go away when the medicine is stopped.
Rare side
effects of magnesium sulfate that may affect the fetus include:
Magnesium sulfate affects both a
mother and her fetus. This medicine:
May reduce risks of
cerebral palsy in the premature newborn if preterm
labor progresses on to preterm delivery during treatment.4
Affects a mother's
central nervous system. Part of normal care when
intravenous magnesium sulfate is given includes checking the mother's reflexes,
usually every 2 to 4 hours, while she is on this medicine.
Affects
the fetus's central nervous system. If a mother is given large doses of
magnesium sulfate, the newborn may have trouble breathing immediately after
birth. But this problem is easily treated with medicine. Some studies show that
magnesium sulfate may increase the risk of death for the baby.1
Can lower a mother's blood pressure and increase her heart rate.
Her blood pressure and pulse are checked frequently for the first few hours of
treatment.
Leaves the mother's body through her urine. The amount
of urine she produces is closely watched to ensure that the medicine does not
build up in her blood.
Grimes DA, Nanda K (2006). Magnesium sulfate
tocolysis: Time to quit. Obstetrics and Gynecology,
108(4): 986–989.
Cunningham FG, et al. (2005). Preterm birth. In
Williams Obstetrics, 22nd ed., pp. 855–880. New York:
McGraw-Hill.
Haas DM (2008). Preterm birth, search date June 2007.
Online version of BMJ Clinical Evidence:
www.clinicalevidence.com.
Rouse DJ, et al. (2008). A randomized, controlled
trial of magnesium sulfate for the prevention of cerebral palsy.
New England Journal of Medicine, 359(9):
895–905.
This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.
