Fever during pregnancy linked to heart defects, facial deformities in baby

A new study published in the journal Science Signaling suggests fever during pregnancy is directly related to the development of heart defects and facial complications like cleft lip and palate, a phenomenon that might be managed with something as simple as Tylenol.

It’s been known since the 1980s that fever in early pregnancy is associated with birth defects like facial irregularities and heart disorders, according to senior author Eric Benner, MD, PhD, but scientists haven’t been able to identify any genetic links or direct causes of the deformities.

Benner and colleagues at Duke Health examined chick and zebrafish embryos and found that, when exposed to magnet-based technology that imitated feverish symptoms in the animals, cells critical to facial and heart composition seemed temperature-sensitive. These neural crest cells, when exposed to transient fever, caused embryos to develop craniofacial irregularities and heart defects.

Hyperthermia seemed to activate TRPV1 and TRPV4 ion channels in neural crest cells, the authors wrote, which are sensitive to high temperatures and give rise to tissues that ultimately create birth defects.

While fevers can’t necessarily be avoided during pregnancy, Benner and co-authors wrote that temperature rises—and therefore possible birth defects—could be managed with judicious use of acetaminophen, or Tylenol, during a woman’s first trimester. Other painkillers, like aspirin, ibuprofen and naproxen, though, should be avoided for the length of a pregnancy.

“My hope is that right now, as women are planning to become pregnant and their doctors advise them to start taking prenatal vitamins and folic acid, their doctor also informs them if they get a fever, they should not hesitate to call and consider taking a fever reducer, specifically acetaminophen, which has been studied extensively and determined to be safe during the first trimester,” Benner said in a Duke Health news release. “While doctors advise most women to avoid any drug during pregnancy, there may be benefits to taking acetaminophen to reduce fever.” Pregnant women should discuss any medication consumption with their doctor prior to taking the drugs, he added, but shouldn’t feel they need to “tough it out” when it comes to fever.

According to Benner’s research, it’s still unknown how severity or length of a fever affects development of these key physical features, but whether a fever affects facial or heart development depends on when in her pregnancy a woman experiences fever.

In the release, a Duke Health obstetrician said fever during pregnancy is far from rare. Avoiding it, she noted, could be as easy as getting an annual flu vaccine and paying extra attention to washing your hands.