Fever Early in Pregnancy may Increase Birth Defect Risk

Women who suffer a fever early in pregnancy may have a slightly increased risk of giving birth to babies with certain birth defects, a review finds.

Numerous studies have suggested a link between fever during pregnancy and increased birth defect risk. The research team found that across 46 studies in the past 20 years, fever during the first trimester — when birth defects typically take shape — was tied to a 50 percent to three-fold increased risk of cleft palate, heart defects and serious malformations of the brain and spine called neural tube defects.

“These are rare events,” said Dr. Siobhan Dolan, an obstetrician and medical advisor to the March of Dimes who was not involved in the review. “So even with an increased risk, the chances of it happening are low.” She said it’s unclear whether it’s the fever or the underlying infection that may be the cause.

Other factors may greatly increase an unborn baby’s risk of developing birth defects. In 2011, the U.S. Food and Drug Administration warned the public about data suggesting infants born to women treated with anti-seizure drug Topamax during pregnancy have an increased risk of developing cleft palate or cleft lip.

Other studies have found that women who take ZofranĀ® during pregnancy may also have an increased risk of having a child with birth defects. Like Topamax, Zofran birth defects include cleft lip and cleft palate, as well as heart defects.

As for the dangers of fevers during pregnancy, acetaminophen — the active ingredient in Tylenol — has been touted a safe and effective fever reducer for pregnant women. So if fever does increase the risk of birth defects, pregnant women can do something about it, Dolan said. A number of studies found the risk of birth defects is lower or gone when moms-to-be treat their fever with acetaminophen or other fever reducers.

Researchers admit there’s a need for long-term studies, and while the review found a possible association between fever during pregnancy and an increased risk of birth defects, it did not prove a cause-and-effect link.

“Usually, the thinking during pregnancy is, ‘Don’t take anything,'” Dolan said. “But this suggests that with fever, the opposite is true. Taking acetaminophen is the way to go.”

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