Ginger appears to help pregnant women who suffer from morning sickness, without side effects to the unborn child, according to a review of the medical literature.

In six studies that examined the effects of ginger in reducing nausea and vomiting in expecting mothers, ginger worked better than a placebo, or inactive drug, and as well as vitamin B6, which has been shown to improve nausea and vomiting in some pregnant women.

None of the women who took ginger had problems with their pregnancies, the authors report in the journal Obstetrics & Gynecology.

“Ginger may be an effective treatment for nausea and vomiting in pregnancy,” write Dr. Francesca Borrelli of the University of Naples Frederico II in Italy and her colleagues.

However, they caution that these data are still “preliminary,” and more studies are needed to confirm that ginger is truly safe for pregnant women.

Up to 80 percent of pregnant women experience morning sickness during the first trimester of pregnancy. While there are many medications designed to ease morning sickness, the authors point out, women often shy away from drugs during pregnancy out of fear of side effects in their unborn children.

As a result, many women turn to alternative treatments, including vitamins, herbal products, homeopathic remedies and acupuncture. Among natural drugs, ginger has long been used to ease nausea, and there is some evidence that the botanical may relieve motion sickness and other types of queasiness.

Indeed, in the U.S., ginger has become one of the top 20 best-selling herbal supplements, with sales of $1.2 million in 2001 alone.

Other commonly used natural products for morning sickness include chamomile, peppermint and raspberry leaf, although none have been studied as extensively as ginger.

To review what has been studied about ginger, Borrelli and colleagues scanned the medical literature, and found six trials that tested ginger in 675 women with nausea in pregnancy.

In four studies that involved a combined total of 246 women, ginger consistently beat out placebo in quelling nausea and vomiting, even in women with a severe form of morning sickness called hyperemesis gravidarum.

In the most recent studies, participants were randomly assigned to take a capsule containing 350 milligrams (mg) of ginger or one containing 25 mg of vitamin B6 three times a day for three weeks.

Ginger was equally effective as vitamin B6 at relieving nausea, vomiting and dry retching. Symptoms of morning sickness improved in a little more than half of the women in each group.

Some studies reported side effects such as headache, diarrhea and drowsiness, but there were no differences in pregnancy outcomes between women taking placebo, vitamin B6 or ginger.

SOURCE: Obstetrics & Gynecology, April 2005.