Magnesium Sulfate Could Damage Newborns’ Bones During Pre-Labor

Magnesium sulfate injections used to treat pre-term labor could cause bone problems in newborns, according to new warnings issued by federal drug regulators.  

In a new drug safety communication issued on May 30, the FDA is recommending against the prolonged use of magnesium sulfate injections to treat pre-term labor.

The FDA indicates that using magnesium sulfate for more than five to seven days to stop pre-term labor in pregnant women may result in low calcium levels in the fetus and potentially cause bone problems, including bone fractures and osteopenia.

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People with osteopenia have low bone mineral density causing the bones to be very thin and at risk of fracture and breaking.

Magnesium Sulfate is currently approved as a treatment to prevent seizures in pregnant women who may be experiencing preeclampsia or to control seizures in women who are already suffering from eclampsia. Preeclampsia and eclampsia are life threatening conditions that can occur during pregnancy. The two conditions may cause pregnant women to suffer from high blood pressure, seizures, organ failure and cause death of the woman or fetus.

Magnesium sulfate injections are often used off-label as a treatment for pre-term labor. Taking the medication to treat pre-term labor is not FDA approved. The shortest amount of time it can be used to treat pre-term labor without resulting in harm to the unborn baby has not been determined.

New Label Warnings to be Added

A teratogenic effects section will also be added to the label, warning users of potential risk to the developing baby which may result in low calcium levels or bone changes.

The pregnancy category for magnesium sulfate will be changed from a D to A rating. Changing the pregnancy category rating signifies there is significant evidence of risk to the fetus. In spite of the risks, benefits of using the medication may be acceptable or necessary under certain conditions.

A labor and delivery section will also be added to warn against the off-label continuous use of magnesium sulfate to treat pre-term labor, especially for more than five to seven days. The FDA adds, the safety of magnesium sulfate for this use has not been established.

Users should be cautious when using the medication off-label to treat other conditions it is not approved for by the FDA. In those situations it should be administered by trained health care professionals or obstetrical personnel in a hospital setting, the FDA warned.

The FDA advises patients at risk of pre-term labor should discuss the benefits and the risks with a health care professional before using magnesium sulfate to treat any condition.


  • meganMarch 2, 2015 at 6:21 pm

    I recently read that magnesium sulfate given before birth can cause this true? I was given mag sul at 38weeks, and my 2 1/2 yr old son was diagnosed with autims.

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