A seizure during pregnancy temporarily disrupts oxygen and blood flow to your baby, but more than 90% of pregnancies in women with epilepsy result in a normal delivery without major complications. The severity of the risk depends on the type of seizure, how long it lasts, and how far along you are. A brief focal seizure (where you stay partially aware) poses far less danger than a prolonged convulsive seizure. Understanding what actually happens in your body during a seizure, and what steps minimize the risks, can help you move from fear to a concrete plan.
What Happens to Your Baby During a Seizure
During a generalized tonic-clonic seizure (the kind involving full-body convulsions and loss of consciousness), several things change at once. Your blood pressure spikes, your oxygen levels fluctuate, and the muscles of your uterus contract. That increase in pressure inside the uterus can squeeze down on the blood vessels that carry oxygen-rich blood to the placenta, temporarily reducing the supply your baby depends on.
The result is a brief period of fetal distress. Your baby’s heart rate may slow significantly, and these changes can persist for about 15 minutes after the seizure ends. In most cases, the baby recovers fully once normal blood flow resumes. However, a prolonged convulsive seizure, particularly one lasting more than five minutes, carries serious risks including fetal death, even when the mother’s own oxygen levels appear adequate. This is why preventing prolonged or repeated seizures is the central goal of managing epilepsy in pregnancy.
Shorter or less intense seizure types, like absence seizures (brief staring spells) or focal seizures that don’t spread to the whole brain, pose much less immediate danger. They don’t typically cause the same dramatic swings in blood pressure and uterine pressure.
Epilepsy vs. Eclampsia: Two Different Causes
Not every seizure in pregnancy comes from epilepsy. Eclampsia is a pregnancy-specific condition that can cause convulsions, and distinguishing between the two matters because the treatments are completely different.
Eclampsia develops as a complication of preeclampsia, which involves high blood pressure (140/90 or higher) and protein in the urine that appear after 20 weeks of pregnancy. If you’ve never had seizures before and suddenly experience one in the second half of pregnancy, especially with swelling, headaches, or vision changes, eclampsia is a likely cause. A woman with known epilepsy who has a seizure earlier in pregnancy is dealing with a different situation entirely. In practice, doctors will check blood pressure and urine protein to sort this out quickly, because eclampsia requires delivery of the baby as the definitive treatment, while epilepsy seizures are managed with ongoing medication adjustments.
Why Seizures Can Increase During Pregnancy
If you already take seizure medication, pregnancy can make it less effective. Your body processes drugs differently when you’re pregnant: your kidneys filter faster, your liver metabolism ramps up, and your blood volume expands significantly. All of this means the medication clears out of your system more quickly, and blood levels can drop below what’s needed to prevent seizures.
The timing varies by medication. Some drugs see their fastest clearance in the first trimester, with blood levels dropping to roughly 60% of their pre-pregnancy baseline. Others peak in the second trimester. Research shows that when medication levels fall below about 65% of a person’s target concentration, the odds of increased seizure frequency go up significantly. This is why doctors typically monitor blood levels of seizure medications throughout pregnancy and adjust doses, sometimes increasing them multiple times. About 1 in 5 women with epilepsy need a dose increase between the first and third trimesters, and some need a second medication added.
Sleep deprivation, stress, nausea-related missed doses, and hormonal shifts all compound the problem. If morning sickness makes it hard to keep pills down, that’s worth discussing with your doctor early rather than waiting for a breakthrough seizure.
Medication Risks to the Baby
The difficult balance of pregnancy with epilepsy is that seizures threaten the baby, but some seizure medications do too. The risk varies dramatically depending on which medication you take.
Valproate (sometimes sold as Depakote) carries the highest known risk. In a large European registry tracking over 7,000 pregnancies, the rate of major birth defects with valproate was around 10%, roughly five times higher than the general population risk. The defects most associated with valproate include spina bifida and other neural tube problems, heart defects, and facial abnormalities.
By contrast, lamotrigine and levetiracetam both showed major malformation rates of about 2 to 3%, which is close to the baseline risk for any pregnancy. These two medications are now the most commonly recommended options for women of childbearing age with epilepsy. If you’re currently on valproate and planning a pregnancy, switching medications before conceiving is strongly preferred, but this should never be done abruptly or without medical guidance, since uncontrolled seizures carry their own serious risks.
Folic Acid: A Higher Dose Than Usual
All pregnant women are advised to take folic acid to reduce the risk of neural tube defects like spina bifida. But if you take seizure medication, the standard prenatal vitamin dose isn’t enough. The recommended dose for women on anti-epileptic drugs is 5 mg daily, which is more than ten times the 400 micrograms typically advised. This higher dose requires a prescription. Ideally, you’d start taking it at least three months before conceiving, since neural tube formation happens in the first few weeks of pregnancy, often before you know you’re pregnant.
What to Do If a Seizure Happens
If you’re with a pregnant person who has a convulsive seizure, the steps are similar to standard seizure first aid with one important addition. Ease them to the ground if they’re falling, and gently roll them onto their left side with their mouth pointing toward the ground. The left side is preferred in pregnancy because it keeps the weight of the uterus off the major blood vessel that returns blood to the heart. Clear the area of anything they could hit, place something soft under their head, and loosen any tight clothing around their neck.
Do not put anything in their mouth or try to restrain them. Time the seizure. The CDC recommends calling 911 for any seizure in a pregnant person, even if they have known epilepsy, because of the added risks to the baby.
Seizure Risk During Labor and Delivery
About 5 to 6% of women with epilepsy experience a seizure during labor or delivery itself. The combination of physical exhaustion, pain, disrupted sleep, and potentially missed medication doses creates a higher-risk window. Most delivery plans for women with epilepsy include continuing seizure medication on schedule throughout labor, and hospitals are prepared to manage a seizure if one occurs.
Having epilepsy doesn’t automatically mean you need a cesarean delivery. Vaginal delivery is appropriate for most women with well-controlled seizures. A C-section is typically reserved for obstetric reasons or situations where seizures are frequent and poorly controlled near the due date.
Breastfeeding on Seizure Medication
Most seizure medications are compatible with breastfeeding. Lamotrigine and levetiracetam, the two most commonly prescribed during pregnancy, both pass into breast milk in moderate amounts but are generally considered safe. Older medications like carbamazepine and phenytoin are also well-established as compatible.
A few medications are contraindicated during breastfeeding, including ethosuximide and zonisamide, which transfer into breast milk at higher concentrations. For any seizure medication, it’s worth watching your baby for signs of excessive drowsiness, poor feeding, or unusual fussiness in the first two months, when their ability to process drugs is most limited.
The Bigger Picture
About 90% of babies born to women with epilepsy are healthy. The key factors that improve outcomes are consistent medication use, dose adjustments guided by blood level monitoring, choosing lower-risk medications before conception when possible, and high-dose folic acid supplementation. The greatest danger comes not from having epilepsy, but from uncontrolled seizures or from stopping medication out of fear of harming the baby. Abruptly discontinuing seizure medication is one of the most dangerous choices in this situation, as it can trigger prolonged seizures that threaten both mother and baby.