Pregabalin, a drug more commonly known by its brand name Lyrica, may cause major birth defects, according to a new study published online in Neurology, the medical journal of the American Academy of Neurology.

Pregabalin is an FDA-approved treatment for epilepsy, fibromyalgia, and neuropathic pain, but it is also prescribed off-label for psychiatric disorders such as generalized anxiety. Off-label prescribing is a legal and common practice in the United States, but it can increase health risks in patients for whom the drug is not intended. Since 2005, over nine million people have been prescribed Lyrica.

To test pregabalin’s link to birth defects, researchers collected data from pregnant women across seven different countries. Of them, 164 took pregabalin during pregnancy while 656 went without it. Seventy-seven percent of the women who took pregabalin started before they became pregnant and, on average, all of the women stopped taking pregabalin six weeks into their pregnancies.

The researchers found that women who took pregabalin were three times more likely to have a child with major birth defects than those who did not take the drug. When the researchers strictly analyzed the pregnancies where pregabalin was used during the first trimester, they found that seven out of 116 pregnancies, or 6 percent, ended with major birth defects when compared to 12 out of the 580 pregnancies, 2 percent, where pregabalin was not used. Pregnancies that resulted in chromosomal birth defects were not included in the study.

The most common birth defects that arose from using the medication included heart defects and structural problems with organs and the central nervous system (CNS). The researchers found that women taking pregabalin were six times more likely to have a pregnancy with a major defect in the CNS when compared to women who had typical pregnancies — 3.2 percent vs. 0.5 percent.

"We can't draw any definitive conclusions from this study, since many of the women [who were taking pregabalin] were taking other drugs that could have played a role in the birth defects,” said study author Dr. Ursula Winterfeld, in a press release. Thirteen percent of women who took pregabalin during pregnancy were also taking another anti-seizure drug. “The study was small and the results need to be confirmed with larger studies, but these results do signal that there may be an increased risk for major birth defects after taking pregabalin during the first trimester of pregnancy.”

The majority of the women included in this study (115 participants) were taking pregabalin for neuropathic pain; however, 39 were taking it for psychiatric disorders, including depression, anxiety, bipolar disorder and psychosis. Only five participants were prescribed pregabalin for epilepsy.

Winterfeld said, "Pregabalin should be prescribed for women of childbearing age only after making sure that the benefits of the drug outweigh the risks and after counseling them about using effective birth control. In cases where women have taken pregabalin during pregnancy, extra fetal monitoring may be warranted."

Source: Winterfeld U, et al. Pregnancy outcome following maternal exposure to pregabalin may call for concern. Neurology. 2016.