Women with Epilepsy: A Handbook of Health and Treatment Issues (Chapter 18)

Family planning and contraceptive choice (Excerpt)

Pamela M. Crawford

Epilepsy treatment and effects on birth control

Epilepsy and its treatment do not alter the effectiveness of any of the nonhormonal methods of birth control. These nonhormonal methods include the intrauterine contraceptive device (IUD), barrier methods (cervical cap, diaphragm, and condom/sheath), the rhythm method and other methods of ‘natural’ family planning with or without spermicides, and sterilization (either tubal ligation for the female or vasectomy for the male).

Hormonal methods involve taking the combined oral contraceptive pill, (which contains two hormones, an estrogen and a synthetic form of progesterone called a progestogen), or the progesterone-only pill (‘mini’ pill), or long-acting preparations such as medroxyprogesterone (Depo-Provera) injections or a depot hormonal implant (Norplant).

Many women with epilepsy may have been told that they cannot take the oral contraceptive pill. This is now known not to be true. The reason that this belief arose was because some of the older drugs used to treat epilepsy speed up the metabolism (the breakdown) of the hormones contained within oral contraceptive pills. This results occasionally in an unplanned pregnancy. If a woman is taking one of the older antiepileptic drugs (AEDs) such as Phenobarbital, phenytoin, mysoline, carbamazepine, or topiramate, she can still take the combined oral contraceptive pill but will need a high dose of estrogen; even so, the failure rate may still be higher than normal. It is best to start with an oral contraceptive pill with at least 50 µg of estrogen and, if breakthrough bleeding occurs, an even higher estrogen dose may be needed. General practitioners, family planning doctors, or gynecologists may be worried about prescribing a higher dose of the combined oral contraceptive pill. However, the estrogen and progesterone which make up the pill are broken down faster than in people who do not take AEDs, so women with epilepsy are not at a greater risk of developing complications such as thrombosis of the veins of the legs.

If it is very important that a woman does not become pregnant and if she is taking one of the drugs that speed up the breakdown of the combined contraceptive pill, she should use an alternative method of contraception or discuss with her neurologist changing her AED to one that does not interact with the contraceptive pill. Taking drugs such as sodium valproate, lamotrigine, gabapentin or vigabatrin for epilepsy means that a woman can take a normal-dose oral contraceptive pill without loss of efficacy. These drugs do not affect the speed of destruction of the contraceptive pill.

There are some types of hormone contraception that do not involve taking a daily pill. Medroxyprogesterone (a type of progesterone hormone) can be given as an intramuscular injection once every 3 months. This is called Depo-Provera. The advantage of this contraceptive is that it frees women from having to think about birth control every day. (Of course, this type of contraceptive does not protect against sexually transmitted diseases, as a condom does.) The does of medroxyprogesterone seems to be high enough to work even in women taking enzyme-inducing AEDs. However, there are no studies directly evaluating the effectiveness of Depo-Provera in women with epilepsy.

Norplant is a contraceptive system that utilizes a progesterone hormone (levonorgesterel) contained within small, silastic-covered rods. These rods are placed under the skin of the inside of the lower arm. The progesterone is slowly released and the system protects against pregnancy for as long as 3 years. However, Norplant has been associated with unplanned pregnancies in women taking AEDs that speed up contraceptive hormone destruction. It seems that the Norplant hormone is broken down so much by enzyme-inducing AEDs that it is not always effective.

-- Excerpted from "Women with Epilepsy: A Handbook for Health and Treatment Issues" edited by Martha J. Morrell, MD and Kerry L. Flynn, M.A. Published by Cambridge University Press, 2003. It is available for purchase in our marketplace.