Magnesium sulfate, an inorganic salt, has many medical uses. One particularly powerful use of magnesium sulfate is for protection of the fetal brain before preterm birth. Studies show that when a fetus is exposed to magnesium sulfate before very preterm birth, the incidence and severity of cerebral palsy decreases significantly.
Exactly how magnesium sulfate protects the baby’s is not well understood. However, professionals hypothesize that in-utero administration of magnesium sulfate may:
- Increase blood flow to the baby’s brain
- Decrease the amount of damaging inflammatory or antioxidant molecules in the baby’s brain
- Reduce levels of excitotoxicity (a process by which neurons are destroyed due to overactive neural receptors)
- Stabilize cell membranes, cerebral blood flow, and blood pressure
How Should Magnesium Sulfate be Administered?
Magnesium sulfate (often administered in conjunction with betamethasone) should be given to women when their baby is expected to be born prematurely (24-32 weeks) within the next 24 hours, whether or not their membranes have ruptured. Generally, medical professionals begin with a 4g dose via IV and provide a 1g maintenance dose every hour for 24 hours, or until the baby is born (whichever is sooner). If it is likely labor will take more than 24 hours, doctors should hold off on beginning magnesium sulfate therapy until closer to the time of delivery. However, if the baby is not doing well and needs to be delivered immediately, doctors should not delay delivery to finish providing magnesium sulfate.
Is Magnesium Sulfate Safe for all Mothers and Babies?
In general, Magnesium sulfate is safe for mothers and babies. However, women with certain neuromuscular diseases, myasthenia gravis, heart problems, or renal (kidney) issues should be very carefully evaluated to prevent magnesium toxicity, and should be very carefully monitored if treatment is given. If doctors decide to use a tocolytic to prevent preterm labor in conjunction with magnesium sulfate, it is likely that indomethacin (a calcium channel blocker) or atosiban will be indicated.