Women with epilepsy may have an increased risk of infertility, especially if they are taking multiple anti-seizure medications, a new study suggests.

The study found that women with epilepsy are more than twice as likely to be infertile than women without the condition. And women who take three or more anti-seizure medications are 18 times more likely to be infertile than women who don't take any epilepsy drugs.

"It appears that the medications do have a negative effect, and it is quite likely that there is a causal relationship," said study researcher Dr. Sanjeev Thomas, of the Sree Chitra Tirunal Institute for Medical Sciences and Technology in India. "But to say that, we need to do more prospective studies."

Anti-seizure drugs have the potential to change the balance of reproductive hormones in the body, previous animal studies have shown, Thomas told MyHealthNewsDaily.

"In turn, that can lead to an infertility state," Thomas said, though that correlation  has yet to be established in humans.

Epilepsy occurs when multiple electrical signals are generated inside the brain, causing seizures. The disorder affects about 2 million Americans, according to the Centers for Disease Control and Prevention.

The study was published Oct. 12 in the journal Neurology.

The infertility link

Researchers observed 375 Indian women about the age of 26 who had epilepsy and planned to become pregnant. The women were followed for 10 years, or until they became pregnant. In that time, 62 percent became pregnant, while 38 percent were infertile, according to the study.

The infertility rate among the general population in India is 15 percent, the study said.

The results showed the risk of infertility increased when more epilepsy drugs were taken.

Seven percent of women who did not take any epilepsy drugs were infertile, 32 percent of women who took one epilepsy drug were infertile, 41 percent of women who took two epilepsy drugs were infertile, and 60 percent of women who took three or more epilepsy drugs were infertile, the study said.

It's unclear whether it's the epilepsy or the drugs that affect infertility, Thomas said. It could be a side effect of the drugs, or it could be that women who have to take more drugs have more severe forms of epilepsy to begin with, he said. Electrical discharges in the brain could lead to an imbalance of reproductive hormones.

That's why more research is needed to determine the true factor affecting infertility, Thomas said.

Discussing pregnancy

The study findings fall in line with a 2009 article in the journal Epilepsy & Behavior, which showed adults with active epilepsy had fewer children than people who stopped having seizures in adulthood.

The new findings also revealed that among women with epilepsy, older women and women with less than 10 years of education had an increased risk of infertility. But that could be because women who have severe epilepsy have a hard time completing additional years of education, Thomas said.

The anti-seizure drugs phenobarbitol and phenytoin were associated with the risk of infertility, but other medications, such as sodium valproate, were not, according to the study.

Thomas said, for most women with epilepsy, particularly those who are young and taking only one medication, there is nothing to be worried about.

"But for those who are taking several drugs and are having more difficult epilepsy," Thomas said, "they may want to discuss pregnancy with their treating physicians"  as to treatment options.

In the study, the women who were able to get pregnant did so within two years of trying. That means if it's taking a woman with epilepsy longer than two years to get pregnant, she should consult with a doctor, Thomas said.