Should Pregnant Women Avoid Antihistamines?

Researchers have found that there may be a link between antihistamine use and adverse outcomes when used by women suffering from hyperemesis gravidarum during pregnancy.

Hyperemesis gravidarum

Doctors sometimes suggest that women suffering from hyperemesis gravidarum (extreme and severe morning sickness) take antihistamines to help them sleep through their nausea. However, researchers from UCLA have discovered that antihistamine use by these women may be linked to adverse outcomes, such as premature birth and low birth weight.

Hyperemesis gravidarum

Hyperemesis gravidarum, otherwise known as extreme and severe nausea and vomiting during pregnancy, only strikes from 0.2 percent to 2 percent of pregnant women. But for those women, HG can be debilitating, landing them in the hospital because they cannot keep down any food or drink or because they are suffering ill effects from the physical act of frequent vomiting, like cracked ribs or detached retinas.

There is no known cause, and treatment generally consists of a few medications that are thought to be effective. Doctors will weigh the risks against the benefits, and if Mom’s illness is causing her to be malnourished, a medication will often be prescribed in hopes that the severe nausea and vomiting will decrease in frequency.

The study

Some doctors will recommend that moms suffering from HG take an over-the-counter antihistamine so she can “sleep away the nausea.” A study, out of UCLA, examined what effects, if any, antihistamines such as Unisom or Benadryl have on pregnancies and babies.

The results, while not totally conclusive, found that moms who resorted to these types of medications reported more adverse outcomes than moms that didn’t. More than 50 percent of women who took these drugs reported negative outcomes, such as premature birth and low birth weight.

"It was surprising to find the link between antihistamines and adverse outcomes as these are over-the-counter medications that are used commonly by women with HG during pregnancy," said Marlena Fejzo, an assistant professor of research in obstetrics and gynecology at UCLA.. "Women and their healthcare providers should be aware of the risk for adverse outcomes when deciding which medications to take to treat their HG symptoms."

The study authors said that more research needs to be done on HG in general and the medications recommended to treat it, and as antihistamines aren’t always effective anyway, moms-to-be should proceed with caution if it’s recommended by their physician.

More on hyperemesis gravidum

Kate Middleton is pregnant, suffers from hyperemesis gravidarum
Second trimester morning sickness tied to increased risks
A nod to nausea


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