Among the different types of AEDs, only EIAEDs were significantly associated with a reason for stopping birth control. For example, menstrual disorder as a reason for stopping birth control was significantly associated with use of EIAEDs. Overall, 29% of respondents who used EIAEDs and hormonal birth control cited menstrual disorder as a reason for stopping, which was twice as often as for women not taking AEDs.
An earlier report from the registry showed that 18% of women on hormonal contraceptives had worsening of their seizures, compared with 3% of women on nonhormonal contraceptives.
These results also led some audience members to wonder who was prescribing AEDs to women on unreliable contraceptive methods such as withdrawal. Indeed, only one-fourth of women who completed the survey consulted a neurologist about what contraceptive methods might be most appropriate for their type of epilepsy and treatment. This was a "surprise," Dr. Herzog said. "Either they don’t think their neurologist know about the topic, or maybe they are correct that [we] don’t know about the topic. And for gynecologists, epilepsy makes up only about 1% of their practice, so it’s not their major focus either."
The investigators now have 550 completed surveys and hope to get 1,000. They are planning to set up a prospective arm of the study in which patients can check back into the registry every 3 months, which will hopefully provide rates of unintended pregnancy for each kind of contraceptive in terms of woman-years of contraceptive use, which is the standard measurement for contraceptive efficacy.
The registry is funded in part by the Epilepsy Foundation. Dr. Herzog and Ms. Saporta had no relevant disclosures.