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

When a woman with epilepsy gets pregnant, she faces a hard choice: keep taking her seizure medication, or stop it to protect the baby. But stopping meds can be just as dangerous as taking them. Uncontrolled seizures during pregnancy can cause miscarriage, premature birth, or even death for both mother and child. At the same time, some seizure medications carry a real risk of causing birth defects. This isn’t a simple decision. It’s a balancing act between two serious risks - and it starts long before pregnancy.

Which Seizure Medications Are Most Dangerous During Pregnancy?

Not all seizure medications are created equal when it comes to pregnancy. Some have been used for decades and come with well-documented risks. Others are newer and much safer. The biggest red flag is valproic acid (also called sodium valproate). Studies show that about 10% of babies exposed to valproate in the womb develop major physical birth defects - things like spina bifida, heart problems, cleft lip or palate, and microcephaly (a smaller-than-normal head size). That’s five times higher than the general population’s risk of 2-3%.

Valproate doesn’t just cause physical defects. Children exposed to it during pregnancy are more than twice as likely to be diagnosed with autism spectrum disorder (ASD) and nearly twice as likely to develop attention deficit hyperactivity disorder (ADHD), according to research from Indiana University. These neurodevelopmental risks stick with the child for life.

Other high-risk medications include carbamazepine, phenobarbital, phenytoin, and topiramate. These drugs also increase the chance of heart defects, facial clefts, and slow fetal growth. The risk goes up with higher doses. For example, taking more than 800 mg of carbamazepine daily during pregnancy raises the chance of birth defects significantly.

But here’s the good news: not all seizure meds are risky. Two of the most commonly prescribed today - lamotrigine and levetiracetam - have been studied extensively and show no major increase in birth defects compared to women not taking any seizure medication. In fact, a Stanford study of 298 children found that those exposed to lamotrigine or levetiracetam in the womb had normal language development at age two. Their verbal skills matched those of children whose mothers didn’t take any seizure drugs.

Why Do Some Seizure Medications Cause Birth Defects?

It’s not just about the drug itself. It’s about how it interacts with the developing fetus. Many antiseizure drugs affect the way cells divide and grow in early pregnancy - especially during the first 12 weeks, when organs are forming. Some interfere with folate metabolism, which is critical for spinal cord and brain development. Others directly disrupt gene expression or cause oxidative stress in fetal tissues.

Valproate is especially problematic because it crosses the placenta easily and stays in the baby’s system longer than other drugs. It also affects enzymes that regulate how the body processes other chemicals needed for healthy development. That’s why even low doses can be dangerous - and why higher doses are far worse.

Older drugs like phenobarbital and phenytoin were developed in the 1950s and 60s, when doctors didn’t fully understand how drugs affected unborn babies. Back then, women with epilepsy were often told not to have children at all. Today, we know better. But the legacy of those early drugs still lingers, especially in places where newer options aren’t available or affordable.

Drug Interactions: Birth Control and Seizure Meds Don’t Mix

Here’s something many women don’t realize: seizure medications can make birth control fail. And birth control pills can make seizure meds less effective. It’s a two-way street that puts women at risk for both unplanned pregnancy and breakthrough seizures.

Drugs like carbamazepine, phenytoin, phenobarbital, and high-dose topiramate speed up how fast the liver breaks down hormones. That means birth control pills, patches, and rings don’t stay in the body long enough to work. A woman on these meds might think she’s protected - but she’s not.

On the flip side, hormonal contraceptives can lower the blood levels of lamotrigine, valproate, zonisamide, and rufinamide. If lamotrigine drops too low, seizures can return. That’s dangerous for both mother and baby. One study found that women taking lamotrigine with birth control pills had seizure breakthroughs in over 30% of cases - even when their doses seemed right.

That’s why women on seizure meds need to talk to their doctor before starting any hormonal birth control. Options like IUDs (especially copper IUDs), implants, or non-hormonal methods are often safer. Some doctors will adjust lamotrigine doses upward when birth control is added - but only under close monitoring.

What About the Risk of Uncontrolled Seizures?

It’s easy to focus only on the drugs. But the real danger isn’t the medication - it’s the seizure. A tonic-clonic seizure during pregnancy can cause oxygen loss to the fetus, placental tearing, premature labor, or even fetal death. Even brief seizures can trigger stress hormones that harm the baby.

Experts agree: uncontrolled epilepsy is more dangerous to a pregnant woman and her baby than any seizure medication. That’s why stopping meds cold turkey is never the answer. The goal isn’t to be completely drug-free. It’s to use the safest possible drug at the lowest effective dose.

One study showed that women who had frequent seizures during pregnancy were three times more likely to have a baby with developmental delays than those whose seizures were well-controlled. The risk of harm from seizures outweighs the risk from most modern medications - if you choose wisely.

What Should Women Do Before Getting Pregnant?

The best time to make changes is before conception. Waiting until you’re pregnant to switch meds is risky. It takes time for new drugs to reach stable levels in your body, and adjusting doses during pregnancy can be tricky.

Here’s what experts recommend:

1. See a neurologist who specializes in epilepsy and pregnancy - not just your regular doctor.
2. Review all current medications. If you’re on valproate, ask if switching to lamotrigine or levetiracetam is possible.
3. Get your blood levels checked for lamotrigine, levetiracetam, or other meds you’re taking.
4. Start taking high-dose folic acid (at least 0.4 mg daily, often 4-5 mg) at least three months before trying to conceive. Folic acid cuts the risk of neural tube defects by up to 70%.
5. Discuss birth control options if you’re not ready to get pregnant yet.
6. Make sure your care team includes an OB-GYN familiar with epilepsy pregnancies.

Many women don’t get this kind of planning. A 2023 study found that only one-third of women of childbearing age with epilepsy received care aligned with their reproductive goals. Too many are left guessing - or worse, prescribed dangerous drugs without knowing the risks.

Is It Safe to Breastfeed While Taking Seizure Medications?

Yes - and it’s encouraged. Most seizure medications pass into breast milk in very small amounts. Lamotrigine and levetiracetam are considered safe for breastfeeding. Even valproate is usually okay in low doses, though doctors will monitor the baby’s liver function.

The benefits of breastfeeding - better immunity, stronger bonding, lower risk of infections - far outweigh the tiny amount of drug the baby gets through milk. The American Epilepsy Society and the CDC both support breastfeeding for women on seizure meds.

Just watch for signs of drowsiness, poor feeding, or unusual irritability in the baby. If you see any, tell your doctor. But don’t stop breastfeeding unless advised.

Are Newer Drugs Making a Difference?

Yes. Between 1997 and 2011, the rate of major birth defects in babies exposed to seizure meds dropped by 39%. Why? Because doctors stopped prescribing valproate to women who could get pregnant. They started using lamotrigine and levetiracetam as first-line options. They began offering preconception counseling. They started tracking doses more carefully.

Today, more women with epilepsy are having healthy babies than ever before. Stanford neurologist Kimford Meador says women should feel “better about their opportunities and options for having a child.” That’s progress.

But gaps remain. A French study found that women with lower income or less access to healthcare were more likely to be prescribed high-risk drugs like valproate. That’s not just a medical issue - it’s a justice issue. Everyone deserves safe, informed care, no matter their background.

Eleven other seizure medications still don’t have enough data to confirm their safety in pregnancy. That means ongoing research is critical. If you’re on one of these drugs, your doctor should be monitoring you closely and documenting outcomes.

Final Thoughts: You’re Not Alone

Deciding what to do about seizure meds during pregnancy is one of the hardest choices a woman can face. There’s no perfect answer. But there is a better path - one based on facts, not fear.

If you’re planning a pregnancy, or even thinking about it, talk to your neurologist now. Don’t wait. Bring up birth control. Ask about folic acid. Find out if your current meds are safe. Bring a partner or family member to the appointment - this isn’t something you should carry alone.

The science has changed. The options are better. And you deserve to have a healthy pregnancy - without being forced to choose between your health and your baby’s.