Hormonal birth control ups epileptic seizures

The use of hormonal contraception among women with epilepsy may significantly increase their rate of seizure activity, according to the findings of a Web-based survey of women aged 18-47 years with the neurological condition.

Seizures while using contraceptives were reported by 18% of women using hormonal contraceptives, compared with 3% of those using non hormonal contraceptives, according to the study’s lead investigator of Beth Israel Deaconess Medical Center, Boston.

When antiepileptic drugs (AEDs) were not used, 24% of women using hormonal contraceptives reported an increase in seizure frequency, compared with 7% of women using nonhormonal contraceptives.

Seizure exacerbation with hormonal contraceptives differed among the AEDs used, said at the meeting, where she presented her findings from the first 300 women who responded to a web-based survey, called the Epilepsy Birth Control Registry.

Valproate showed the greatest seizure exacerbation when used in conjunction with hormonal contraceptives. Seizures exacerbation while taking valproate occurred in 44% of women using hormonal contraceptives, compared with 8% of women who were using nonhormonal contraceptives.

In general, glucuronidated AEDs and enzyme-inducing AEDs were associated with significantly greater seizure exacerbation than nonenzyme-inducing AEDs, especially when women were using hormonal contraception.

In a related analysis that looked more broadly at contraceptive choices among the same group of surveyed women, 72% of the women reported using contraception. Among those women, the most common choices were oral contraceptives (23%) male condoms (23%) intrauterine devices (12%) and withdrawal (10%).

“Although contraception is an important consideration for women of reproductive age, there has been little investigation of contraceptive practices in women with epilepsy,” said at Beth Israel Deaconess Medical Center.

The top three considerations when making contraceptive choices were AED interaction (57%) efficacy (53%) and convenience (45%). Only about 3% of the women mentioned cost as a most important consideration in choosing contraception.

A subgroup of 178 women was deemed high risk because they were potentially fertile and sexually active. Of these women, 68% used highly effective contraceptive methods: 44% used hormonal contraception, 16% used IUDs, and 8% relied on tubal ligation or vasectomy.

Hormonal contraception varied according to insurance coverage status (53% with insurance used it vs. 29% without).

Only 28% of the women reported consulting their neurologist before selecting a contraceptive method.

The retrospective design of both studies limited the conclusion that could be drawn. “Prospective investigations are needed to determine whether these findings represent important seizure safety issues or reporting biases.”