Epilepsy and contraception

For many women decisions about starting birth control and choosing a birth control method can be challenging. If you have epilepsy, your choice requires even more thought because some anti-epilepsy medication can make some types of birth control less effective.

If  a method of contraception does not work well, this can lead to pregnancy, which can be a problem because some antiepileptic medicines like sodium valproate, can harm your baby. Read more about epilepsy and pregnancy.

If you are taking antiepileptic medicine and are a woman of child-bearing age, it is important that you also use contraception. The risk of harm to the baby from antiepileptic medicine use during pregnancy is highest in the first trimester (first 12 weeks of pregnancy), before many women realise they are pregnant.

It is best to use two forms of contraception, usually one of the options in the table below plus condoms. If you are taking an oral contraceptive, make sure you know what to do if a dose is missed or if you are sick with vomiting or diarrhoea.

How well does contraception work?

Intrauterine devices (IUD) and implants are the most reliable methods of contraception. They are most effective in preventing pregnancy. Using condoms as your only protection is least reliable. Condoms are best used together with another method of contraception. 

Contraceptive method Description
Intrauterine device (IUD)
  • Very reliable – fewer than 1 in every 100 women (1%) become pregnant during one year of typical use.
  • It is not affected by anti-epilepsy medication.
  • An IUD is a small, T-shaped plastic device that is inserted into your uterus (womb) and has a plastic string tied to the end which hangs down through the cervix into the vagina.
  • In New Zealand, there are two types of IUDs: progestogen or hormonal IUDs (such as Mirena®, Jaydess®) and copper IUD.
  • Read more about IUDs.
Progesterone-only implant 
  • Very reliable – fewer than 1 in every 100 women (1% become pregnant during one year of typical use.
  • This option is NOT recommended if you are taking carbamazepine, phenytoin, oxcarbazepine, phenobarbital, primidone, rufinamide, or topiramate.
  • The contraceptive implants are small rods (about the size of a matchstick) that contain progesterone. These rods are placed under the skin, in the inside of your arm (you can feel the rods under your skin).
  • Read more about implants.
Medroxyprogesterone acetate injections (Depo Provera)
  • About 6 in every 100 women (6%) become pregnant during one year of typical use.
  • It is not affected by anti-epilepsy medication.
  • Depo Provera is given as an injection, every 12 weeks (every 3 months).
  • Read more about Depo Provera.
Combined hormonal oral contraceptive (COC)
pill or vaginal ring
  • About 9 in every 100 women (9%) become pregnant during one year of typical use.
  • This option is NOT recommended if you are taking carbamazepine, phenytoin, lamotrigine, oxcarbazepine, phenobarbital, primidone, rufinamide, topiramate.
  • The effectiveness of the COC pill is highly dependent on taking it every day, whether you have sex on that day or not.
  • If you are taking an oral contraceptive, make sure you know what to do if a dose is missed or if you are sick with vomiting or diarrhoea.
  • Read more about combined hormonal oral pill or vaginal ring
Progesterone-only pill (POP)  
  • About 9 in every 100 women (9%) become pregnant during one year of typical use.
  • This option is NOT recommended if you are taking carbamazepine, phenytoin, oxcarbazepine, phenobarbital, primidone, rufinamide or topiramate.
  • The effectiveness of the POP is highly dependent on taking it every day.
  • Read more about progesterone-only pill
Condoms
  • Very unreliable – about  18 in every 100 women (18%) become pregnant during one year of typical use.
  • If you are taking antiepileptic medicine, it is best to use one of the options above together with condoms.

Emergency contraceptive pill ('the morning after pill')

The 'morning-after pill' is a form of emergency contraception that can be taken within 72 hours after sex. It can be used if you have unprotected sex, if you have missed a dose of the pill or if a condom breaks.

  • Some anti-epilepsy medication can affect the morning-after pill such as taking carbamazepine, phenytoin, oxcarbazepine, phenobarbital, primidone, rufinamide, topiramate.
  • The dose of the morning-after pill will need to be doubled. however, this is an unapproved dose and the effectiveness of this option has not been fully studied.
  • A copper IUD is recommended for emergency contraception for women taking these antiepileptic medicines.

Do contraceptives increase the chance of seizures?

Non-hormonal contraceptive methods (such as condoms, diaphragms, and IUDs) do not affect seizure control. The effect of hormonal contraception (such as the combined oral contraceptive, mini pill or progesterone only pill) and implant on seizure control varies among women.

  • Some women find that hormonal birth control increases their number of seizures while other women find it decreases their seizures, or has no effect on their seizures at all.
  • If you are unsure of the effect of your birth control method on your seizures, look for signs that your epilepsy medication is not working, such as changes in the number, length, or kind of seizures you usually have. Talk to your doctor about this.

If you are planning a pregnancy

If you decide you would like to get pregnant, it is important to plan your pregnancy 6 to 12 months before you start trying to get pregnant. Antiepileptic medicines can harm an unborn child and the risks are higher with some medicines, combinations of medicines and at higher doses. Talk to your doctor and agree on a plan about how to manage your antiepileptic medicines and your dose. Read more about the risks and benefits of taking anti-epilepsy medicines.

Folic acid

Folic acid tablets are recommended from four weeks before, to at least 12 weeks after conception to reduce the risk of harm to your baby from neural tube defects. A higher than usual dose of folic acid (5 mg per day) is recommended for women taking antiepileptic medicines. Folic acid reduces the risk of harm from neural tube defects but does not reduce other harmful effects of antiepileptic medicines to the baby. Read more about folic acid.

Learn more

Contraception Epilepsy New Zealand
Planning for a baby Epilepsy New Zealand
Epilepsy and women Epilepsy New Zealand
Are you taking medicines for epilepsy, mood or pain? ACC, New Zealand 

References

  1. Balancing the benefits and risks of prescribing antiepileptic medicines in women BPAC, 2018
Credits: Sandra Ponen, pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 24 Oct 2018