Seizure Medications and Pregnancy: Risks of Birth Defects and Drug Interactions

When a woman with epilepsy becomes pregnant, she faces a difficult choice: keep taking her seizure medication to prevent dangerous seizures, or stop it to protect her baby - only to risk life-threatening seizures for both. This isn’t a hypothetical dilemma. It’s a daily reality for thousands of women. And the truth is, seizure medications can affect a developing baby - but so can uncontrolled seizures.

Some Seizure Medications Carry High Risks

Not all antiseizure drugs are the same when it comes to pregnancy. Some have been around for decades and come with well-documented dangers. Sodium valproate (valproic acid) is the most concerning. Around 10% of babies exposed to it during pregnancy develop major birth defects - nearly double the rate seen with other medications. These include heart problems, cleft lip or palate, spinal cord issues, and microcephaly (a smaller-than-normal head size). Studies also show these children are more than twice as likely to be diagnosed with autism or ADHD later in life.

Other older drugs like carbamazepine, phenytoin, phenobarbital, and topiramate also raise the risk of physical birth abnormalities, though not as sharply as valproate. For example, carbamazepine increases the chance of heart defects and neural tube problems, especially at higher doses. Phenytoin is linked to fetal hydantoin syndrome, which can cause facial deformities, slow growth, and intellectual delays. Topiramate, even at lower doses, has been tied to cleft lip and low birth weight.

These risks aren’t random. They’re tied to how the drugs interact with fetal development. Some interfere with folate metabolism - a key nutrient for neural tube formation. Others directly affect cell growth in the brain and organs. The higher the dose, the greater the risk. That’s why doctors now push for the lowest effective dose - not just for seizure control, but for fetal safety.

Safer Options Exist - and They’re Widely Available

The good news? Not all seizure medications are risky during pregnancy. Lamotrigine (Lamictal) and levetiracetam (Keppra) have been studied extensively and show no significant increase in major birth defects compared to the general population. In fact, they’re now the go-to choices for women planning pregnancy.

A 2021 Stanford study followed 298 children whose mothers took newer antiseizure drugs during pregnancy. At age two, their verbal skills were on par with children of mothers without epilepsy. While some subtle developmental differences were noted at very high drug levels, the overall picture was reassuring. These newer drugs - lamotrigine and levetiracetam especially - don’t appear to disrupt brain development the way older ones do.

The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) confirms this. Their 2023 review found that lamotrigine and levetiracetam are the safest options currently available. Many neurologists now start women on these drugs before conception, even if they were previously stable on older medications. The goal isn’t just to avoid seizures - it’s to avoid harm to the baby, too.

Drug Interactions Can Undermine Both Birth Control and Seizure Control

Here’s something many women don’t realize: seizure medications can mess with birth control - and vice versa. Some antiseizure drugs, like carbamazepine, phenytoin, phenobarbital, and high-dose topiramate, speed up how the body breaks down hormones. That means birth control pills, patches, or rings can become less effective. Women on these drugs may think they’re protected - but they’re not.

On the flip side, hormonal contraceptives can lower the levels of certain antiseizure drugs in the blood. Lamotrigine is especially vulnerable. When a woman starts taking birth control pills, her lamotrigine levels can drop by half. That raises the risk of breakthrough seizures - sometimes dangerously so. The same thing can happen with valproate, zonisamide, and rufinamide.

This isn’t a minor side effect. It’s a clinical emergency waiting to happen. A woman might be doing everything right - taking her meds, using birth control - and still end up with an unplanned pregnancy or a seizure in the middle of the night. That’s why doctors now check drug levels regularly when a woman starts or stops hormonal contraception. Sometimes, a higher dose of lamotrigine is needed. Sometimes, switching to a non-hormonal method like an IUD is the safest choice.

Uncontrolled Seizures Are Even More Dangerous

It’s easy to focus only on the risks of medication. But let’s be clear: having a tonic-clonic seizure during pregnancy is far more dangerous than taking lamotrigine. Seizures can cause oxygen deprivation, physical trauma, miscarriage, premature labor, or even death for both mother and baby. One study found that women with poorly controlled epilepsy had a 10 times higher risk of fetal death than those with good seizure control.

This creates what experts call an "excruciating double bind." You need the drug to prevent seizures. But the drug might hurt the baby. The answer isn’t to stop medication. It’s to choose the right medication - at the right dose - and monitor closely.

The American Epilepsy Society and the NIH both agree: never stop your seizure medication without medical supervision. The risk of uncontrolled seizures outweighs the risk of most modern antiseizure drugs. The goal is balance - not avoidance.

Preconception Planning Is Non-Negotiable

The best time to talk about seizure medications and pregnancy isn’t after you find out you’re pregnant. It’s before you even try. Yet a 2023 study found that two-thirds of women of childbearing age with epilepsy answered basic questions about medication safety incorrectly. Only one in three received care that matched their reproductive goals.

That’s why preconception counseling is now standard. A neurologist should review your current meds, switch you to safer options if needed, adjust your dose, and check your folate levels. Folic acid supplements - at least 0.4 mg daily, often higher - are recommended for all women with epilepsy planning pregnancy. They help reduce the risk of neural tube defects.

Women on valproate should be strongly advised to switch - if possible - before conception. If valproate is the only thing that controls their seizures, the risks must be weighed carefully, and the dose should be kept as low as possible. But in most cases, alternatives exist.

Progress Is Real - But Inequality Remains

There’s good news: between 1997 and 2011, the rate of major birth defects in babies exposed to antiseizure drugs dropped by 39%. That’s thanks to better prescribing, more awareness, and the use of safer drugs like lamotrigine and levetiracetam.

But progress isn’t equal. 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 during pregnancy. They were also less likely to receive preconception counseling. This isn’t about individual choices - it’s about systemic gaps in care.

There are still 11 antiseizure drugs with insufficient data on pregnancy safety. That means some women are being treated with drugs we simply don’t know enough about. Ongoing research is critical.

What Women Need to Know Right Now

• If you’re on valproate and planning pregnancy, talk to your doctor about switching - now.
• Lamotrigine and levetiracetam are the safest options for pregnancy - if they work for your seizures.
• Birth control pills, patches, or rings may not work if you’re on carbamazepine, phenytoin, phenobarbital, or high-dose topiramate.
• If you’re on lamotrigine and start hormonal birth control, your drug levels may drop. Tell your neurologist immediately.
• Never stop your seizure medication without medical advice - even if you’re trying to get pregnant.
• Take high-dose folic acid (at least 0.4 mg, often 5 mg) before and during pregnancy.
• Get preconception counseling from a neurologist who specializes in epilepsy and pregnancy.

More than 90% of babies born to women with epilepsy are healthy. That’s not luck. It’s careful planning, better drugs, and informed choices. You don’t have to choose between being a good mother and being a healthy one. With the right care, you can be both.