Women who are pregnant or trying to conceive should steer clear.

An ingredient found in supplements marketed for weight loss and cognitive enhancement might increase women’s chances of suffering from a miscarriage, the FDA says.

The administration warned in a statement yesterday that vinpocetine, a common ingredient in dietary supplements, may cause miscarriage or harm fetal development. “That’s why today we’re advising pregnant women and women who could become pregnant not to take vinpocetine, the statement reads.

According the European Journal of Pharmacology, vinpocetine is a man-made ingredient derived from the extract of the periwinkle plant. The FDA notes that it may be referred to on product labels as common periwinkle extract, Vinca minor extract, or lesser periwinkle extract.

Supplements that contain vinpocetine often claim to help users with memory, mental acuity, or focus; weight loss; and increased energy. They may also be marketed as a preventative against Alzheimer’s disease and dementia.

The FDA reviewed data from the National Institutes of Health’s National Toxicology Program before issuing the warning. The statement cites research that found that vinpocetine made pregnant animals more likely to have a miscarriage. Additionally, the ingredient decreased fetal weight in animals, as well.

The findings of animal studies do not always translate to human health outcomes. But because the amount of vinpocetine found in the blood of the pregnant animals that were studied was similar to the amount that has been found in the blood of humans after just one dose of the ingredient, the FDA stated that “pregnant women may experience adverse effects from vinpocetine similar to those seen in the pregnant animals.”

The new statement also calls for action on the part of dietary supplement manufacturers. Specifically, it calls on industry leaders to “evaluate their product labeling to ensure that it provides safety warnings against use by pregnant women and women who could become pregnant.” The statement says the effects of vinpocetine are “particularly concerning since products containing vinpocetine are widely available for use by women of childbearing age.” It also notes that the number of products on the market containing this ingredient has grown, and that labels often have no warnings about risks to pregnant women and fetal development.

In some countries, vinpocetine is only available as a prescription drug. The FDA statement highlights the fact that just because a product is commercially available in the United States doesn’t mean it’s safe. “When products like vinpocetine are sold as dietary supplements in the US, they have not been reviewed by the FDA under the safety and effectiveness standards that apply to drug products,” the statement says.