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Women who received magnesium sulfate during labor were less likely to develop maternal fever, a condition that can lead to a variety of complications in newborns including difficulty breathing, seizures, cerebral palsy and a condition known as “floppy baby syndrome,” characterized by inadequate muscle tone, according to a retrospective study presented at the ANESTHESIOLOGY® 2015 annual meeting in San Diego.

Elizabeth Lange, M.D., lead author of the study and obstetrical anesthesiology attending physician at Northwestern Memorial Hospital in Chicago, and colleagues studied data from live births at Northwestern Memorial Hospital between 2007 and 2014. Nearly 63,000 deliveries met the study criteria.

According to the data, 6,163 laboring mothers developed maternal fever (9.8 percent), defined as a temperature of 100.4 degrees Fahrenheit or above. These women tended to be first-time mothers, full term, were not preeclamptic (characterized by high blood pressure), had received an epidural or spinal anesthesia and required cesarean delivery. Among those who developed fevers, 2,190 received intravenous magnesium during their labor for the prevention or management of other pregnancy-related conditions. 

Maternal fever was found to be lower in women who received magnesium than those who did not (4.3 percent vs. 9.9 percent).

Dr. Lange’s study is the first-of-its-kind to focus on the association between magnesium sulfate and maternal fever. Previous animal studies have demonstrated the ability of magnesium sulfate to suppress certain signaling molecules in the immune system called interleukin-6, which are thought to modulate maternal temperature.

“The most important finding in this study is that magnesium appears to have a protective effect on maternal fever during labor,” said Dr. Lange. “By reducing the incidence of maternal fever, magnesium sulfate therapy may also reduce the incidence of complications in newborns.”

The study noted that there is a known association between epidural and spinal anesthesia and fever. Dr. Lange said that further studies should be done to determine how best to use magnesium sulfate to prevent fever, looking at factors such as how long magnesium should be administered.


Founded in 1905, the American Society of Anesthesiologists (ASA) is an educational, research and scientific society with more than 52,000 members organized to raise and maintain the standards of the medical practice of anesthesiology. ASA is committed to ensuring physician anesthesiologists evaluate and supervise the medical care of patients before, during and after surgery to provide the highest quality and safest care every patient deserves.


For more information on the field of anesthesiology, visit the American Society of Anesthesiologists online at To learn more about the role physician anesthesiologists play in ensuring patient safety, visit Join the ANESTHESIOLOGY® 2015 social conversation today. Like ASA on Facebook, follow ASALifeline on Twitter and use the hashtag #ANES2015.

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