Seizure Medications and Pregnancy: Birth Defect Risks and Drug Interactions You Need to Know

When you’re taking medicine to control seizures, the last thing you want to worry about is whether it might harm a baby you’re planning to have. But the truth is, some seizure medications carry real risks during pregnancy - not just for the baby, but for the mother too. And if you’re using birth control at the same time, things get even more complicated. It’s not about scaring you. It’s about giving you clear, real facts so you can make smarter choices - with your doctor.

Some seizure meds are far riskier than others

Not all antiseizure medications (ASMs) are created equal when it comes to pregnancy. Back in the 1960s and 70s, doctors didn’t have good data. Many women with epilepsy were told not to have kids at all. That changed as treatments improved, but some of the older drugs turned out to be dangerous.

Take sodium valproate a commonly prescribed antiseizure medication that has been linked to severe birth defects and developmental disorders in children exposed during pregnancy. It’s one of the most effective drugs for stopping seizures. But it’s also one of the riskiest for unborn babies. About 1 in 10 babies exposed to valproate in the womb develop major physical birth defects - things like heart problems, cleft lip or palate, or spinal cord issues. The risk goes up the higher the dose. And it’s not just physical. These children are more than twice as likely to be diagnosed with autism or ADHD later in life, according to research from Indiana University published in Neurology in 2020.

Other high-risk drugs include carbamazepine an antiseizure medication that increases the risk of physical birth abnormalities, especially at higher doses, phenobarbital a barbiturate used for seizure control with known teratogenic effects during pregnancy, phenytoin a long-standing antiseizure drug associated with increased rates of congenital malformations, and topiramate an antiseizure medication that can increase the risk of cleft lip/palate and low birth weight. The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) confirms these four carry clear risks.

But here’s the good news: newer medications like lamotrigine an antiseizure medication with a favorable safety profile during pregnancy and levetiracetam an antiseizure medication with minimal risk of birth defects and no known major teratogenic effects are much safer. Studies from Stanford in 2021 followed 298 children exposed to these drugs before birth. At age two, their language skills were just as strong as children whose mothers didn’t take any seizure meds. The risk of major birth defects with these two is close to the general population rate - around 2-3%.

What kinds of birth defects can happen?

It’s not just one thing. Different drugs are linked to different problems:

• Heart defects - like holes in the heart or abnormal blood flow. Seen in 1-2% of babies exposed to high-risk ASMs.
• Cleft lip or palate - more common with topiramate and valproate.
• Spinal cord problems - such as spina bifida, especially with valproate.
• Microcephaly - a smaller-than-normal head size, seen in about 0.5-1% of valproate-exposed babies.
• Slow growth - babies may be born smaller or gain weight slowly after birth.
• Urinary tract issues - kidney or bladder abnormalities reported in some cases.

And while these sound scary, remember: more than 90% of babies born to mothers with epilepsy are healthy. The key isn’t avoiding medication - it’s choosing the right one.

Drug interactions can make things worse

If you’re using hormonal birth control - pills, patches, or rings - you might not realize your seizure meds are fighting each other. Some ASMs make birth control less effective. That means you could get pregnant even if you’re taking your pill every day.

Drugs like carbamazepine, phenytoin, phenobarbital, oxcarbazepine, and high-dose topiramate speed up how your body breaks down hormones. That lowers the amount of birth control in your system.

And it goes both ways. Hormonal birth control can make some seizure meds less effective. That’s especially true for lamotrigine, valproate, zonisamide, and rufinamide. If your seizure control slips, you’re at risk for dangerous tonic-clonic seizures - which can cause miscarriage or injury to both you and the baby.

So if you’re on birth control and an ASM, talk to your doctor. You might need a higher-dose pill, a non-hormonal IUD, or even a different seizure medication. Don’t assume your pharmacy or your pill pack has it covered.

Why you shouldn’t stop your meds on your own

It’s tempting. If you’re worried about birth defects, you might think, “I’ll just quit my meds.” But that’s dangerous. Uncontrolled seizures are a major threat. A single tonic-clonic seizure during pregnancy can cause oxygen loss, falls, trauma, or even miscarriage. The American Epilepsy Society says clearly: no ASM is as dangerous to a pregnant person or their baby as uncontrolled seizures.

That’s why experts call it an “excruciating double bind.” You need the medicine to stay safe. But the medicine might hurt the baby. The answer isn’t choosing one over the other - it’s choosing the right one.

Preconception counseling isn’t optional - it’s essential

If you’re a woman of childbearing age and take seizure meds, you need to talk to your neurologist before you even try to get pregnant. This isn’t a one-time chat. It’s part of your ongoing care.

Here’s what should happen:

1. Review your current medication. If you’re on valproate, switching to lamotrigine or levetiracetam should be seriously considered - even if your seizures are well controlled.
2. Use the lowest effective dose. Higher doses = higher risk. Your doctor should aim for the minimum amount that keeps you seizure-free.
3. Check your birth control. If you’re on hormonal methods, ask if your ASM is making them less effective. Switch to an IUD or implant if needed.
4. Start taking folic acid. At least 0.4 mg daily, and sometimes up to 5 mg if you’re on high-risk meds. Folic acid lowers the risk of neural tube defects.
5. Plan your timeline. Don’t wait until you miss a period. Get your meds adjusted before conception.

A 2023 study in Neurology found that women with lower income or fewer healthcare resources were more likely to be on high-risk drugs during pregnancy. That’s not because they made bad choices - it’s because they didn’t get the right advice. Access to specialists matters.

The big picture: things are getting better

There’s real progress. Between 1997 and 2011, the rate of major birth defects linked to seizure meds dropped by 39%. Why? Better prescribing. More awareness. More women getting preconception care.

Stanford’s 2021 study showed that children exposed to newer ASMs like lamotrigine and levetiracetam had normal language development. That’s huge. It means you can have a healthy baby and still manage your epilepsy.

But we’re not done. Eleven other ASMs still don’t have enough data to say whether they’re safe in pregnancy. And too many women are still being prescribed valproate without knowing the risks.

What you can do right now

• If you’re on valproate, phenobarbital, phenytoin, carbamazepine, or topiramate - ask your doctor if you can switch.
• If you’re on lamotrigine or levetiracetam - you’re already on a safer path. Keep taking it.
• If you’re on birth control - tell your neurologist what you’re using. Ask if your seizure meds interfere.
• If you’re planning pregnancy - schedule a preconception visit. Don’t wait.
• If you’re not planning pregnancy - use reliable contraception. Talk to your doctor about what’s safest with your meds.

You don’t have to choose between being seizure-free and being a parent. With the right care, you can be both.

If you’re thinking about having a baby and take seizure meds, you’re not alone. Thousands of women do it every year. With the right care, the risks are manageable. The goal isn’t to avoid pregnancy - it’s to make sure you and your baby both stay safe.