Pregnancy can change both seizure control and the way the body handles antiseizure medicines. For many people with epilepsy, pregnancy is uncomplicated and seizures remain stable. For others, medication concentrations fall, seizures increase or treatment needs adjusting. The safest approach is coordinated care between the epilepsy team, specialist maternity services and primary care.
This page focuses on what happens during pregnancy. Preconception planning, folic acid, contraception, valproate and topiramate are covered separately so that those topics can be explained in full without repeating them here.
Pregnancy does not affect everyone’s seizures in the same way
Some people have no meaningful change in seizure frequency during pregnancy. Some improve. Others experience more seizures.
The reasons vary and can include falling antiseizure medicine concentrations, vomiting, missed doses, sleep disruption, stress, changes in adherence, altered metabolism and the natural variability of the epilepsy itself.
A seizure increase should never automatically be blamed on “pregnancy hormones”. Medication levels and other practical causes need to be considered as well.
Specialist epilepsy care should continue throughout pregnancy
NICE recommends that women and girls with epilepsy who are pregnant are referred to an epilepsy specialist team and that information is shared between the epilepsy team, specialist obstetric team and primary care.
More frequent reviews may be appropriate for people with active epilepsy, bilateral tonic-clonic seizures, learning disability, age under 16 or modifiable SUDEP risk factors.
Do not stop antiseizure medicines because pregnancy has begun
Stopping treatment without medical supervision can cause breakthrough seizures, clusters or status epilepticus.
The correct balance is between fetal exposure to medication and the risks of poorly controlled seizures. Those risks must be assessed together rather than treating medicine exposure as the only concern.
Pregnancy changes drug pharmacokinetics
Pregnancy changes blood volume, kidney filtration, liver enzyme activity, protein binding and body composition. These changes can alter how quickly antiseizure medicines are distributed, metabolised and eliminated.
The effect is not the same for every medicine or every person.
Lamotrigine can fall substantially
Lamotrigine is one of the clearest examples of pregnancy-related pharmacokinetic change. Its clearance commonly rises during pregnancy, which can cause blood concentrations to fall even when the prescribed dose has not changed.
For someone whose seizure control depends on a particular lamotrigine concentration, a substantial fall may lead to breakthrough seizures.
Monitoring can therefore be useful where clinically indicated, especially when a preconception baseline concentration is available.
Levetiracetam concentrations can also fall
Levetiracetam clearance can increase early in pregnancy. Prospective data have found measurable changes from the first trimester, with some people requiring dose increases to maintain their individual target concentration.
The amount of change varies widely between individuals, so dose adjustments should be based on clinical review rather than a universal pregnancy dose.
Oxcarbazepine and other medicines can change too
Pregnancy-related clearance changes have also been described with oxcarbazepine, phenytoin, phenobarbital, topiramate and zonisamide.
NICE specifically identifies carbamazepine, lamotrigine, levetiracetam, oxcarbazepine, phenobarbital and phenytoin as medicines for which monitoring and dose adjustment may be considered during pregnancy in line with MHRA advice.
Drug-level monitoring is individualised
There is no rule that every pregnant person with epilepsy must have every antiseizure medicine level checked at fixed intervals.
NICE recommends considering monitoring when seizure worsening is a concern and using a preconception concentration as a personal baseline where monitoring is planned.
The result should be interpreted with seizure control, adherence, side effects and the individual’s previous effective level.
A “normal laboratory range” is not always the target
Therapeutic ranges are population guides. During pregnancy, the most useful comparison may be the person’s own pre-pregnancy concentration when seizures were well controlled.
A concentration that remains within the laboratory reference interval may still represent a clinically important fall for that individual.
Seizure diaries become particularly useful
Recording seizure dates, type, duration, missed doses, vomiting, sleep disruption and medication changes can help clinicians distinguish an isolated seizure from a developing pattern.
A diary can also show whether seizure worsening coincides with a falling drug concentration or a dose change.
Vomiting can interfere with medication
Nausea and vomiting are common in pregnancy, particularly early pregnancy. Repeated vomiting can interfere with reliable absorption of antiseizure medicine.
If a dose is vomited shortly after it is taken, advice should be sought about whether to repeat it. This depends on the medicine, formulation and timing.
Severe or persistent vomiting may need urgent maternity review because dehydration and missed treatment can both increase seizure risk.
Sleep remains important
Poor sleep can worsen seizures in some people. Pregnancy itself can disrupt sleep through nausea, reflux, discomfort, urinary frequency, restless legs, anxiety and later fetal movement.
Sleep protection is therefore part of epilepsy management rather than an optional lifestyle extra.
What if seizures increase during pregnancy?
A meaningful increase in seizure frequency should trigger review rather than simply being accepted as a normal pregnancy change.
Clinicians may consider adherence, vomiting, sleep loss, intercurrent illness, new medications, antiseizure drug concentrations and the possibility that the epilepsy itself has changed.
Depending on the cause, treatment may involve correcting missed doses, treating another illness, adjusting medication or increasing monitoring.
One breakthrough seizure does not automatically mean treatment has failed
Clinical context matters. A single seizure following a missed dose or severe sleep deprivation may have a different implication from repeated unprovoked seizures despite correct medication use.
Pregnancy treatment decisions should therefore look at pattern and cause, not only the raw seizure count.
Bilateral tonic-clonic seizures deserve particular attention
Bilateral tonic-clonic seizures can cause falls, injury and transient changes in oxygenation and circulation. Prolonged seizures are a medical emergency.
People with a history of bilateral tonic-clonic seizures may need more frequent review, particularly if seizures are active during pregnancy.
Status epilepticus remains an emergency
Status epilepticus during pregnancy requires urgent treatment. Pregnancy does not remove the need for standard emergency seizure care.
Emergency clinicians must balance maternal stabilisation with fetal considerations, but controlling prolonged seizures is itself essential to protect both.
Anyone with an established rescue-medication plan should make sure maternity and emergency teams know what it contains.
When should emergency services be called?
The same general seizure-emergency principles apply during pregnancy, with a lower threshold for concern where there is injury or pregnancy-related complication.
Emergency assessment is particularly important for a prolonged seizure, repeated seizures without recovery, serious injury, breathing difficulty, a first-ever seizure, significant abdominal trauma, heavy bleeding, severe headache with neurological symptoms or a seizure pattern that is clearly different from usual.
See When to Call Emergency Services and Status Epilepticus & Rescue Medication.
A first seizure in pregnancy is not automatically epilepsy
A new seizure during pregnancy needs urgent assessment because there are pregnancy-specific and non-epileptic causes that must be considered.
These include eclampsia, metabolic disturbances, infection, cerebral venous thrombosis, stroke and other acute neurological disorders.
A person with established epilepsy can also develop an unrelated pregnancy complication, so a changed seizure pattern should not automatically be attributed to their known diagnosis.
Eclampsia is a different emergency
Eclampsia refers to seizures associated with hypertensive disease of pregnancy. It is managed as an obstetric emergency and is not the same as a recurrence of epilepsy.
Severe headache, visual disturbance, high blood pressure, upper abdominal pain, swelling or other symptoms of pre-eclampsia alongside a seizure need urgent maternity assessment.
MRI can still be used when clinically necessary
Pregnancy does not prevent neurological investigation when it is needed.
MRI without contrast is generally used when clinically indicated because it does not involve ionising radiation. The decision to use contrast requires additional consideration and should be made by the treating team based on clinical necessity.
EEG can be performed during pregnancy
EEG does not expose the fetus to radiation and can be used when clinically indicated.
As outside pregnancy, a normal EEG does not exclude epilepsy and an abnormal EEG must be interpreted alongside the clinical history.
Fetal screening and monitoring
Pregnancy care for someone taking antiseizure medicines may include detailed fetal structural assessment and, where clinically indicated, additional growth monitoring.
The exact schedule depends on the antiseizure medicine, obstetric history and fetal findings.
Medicines associated with fetal growth restriction, including topiramate, phenobarbital and zonisamide in current MHRA reviews, may prompt particular attention to fetal growth.
Screening cannot predict every outcome
Ultrasound can identify many structural abnormalities but cannot rule out all congenital conditions or predict later cognition, behaviour and neurodevelopment.
This is why medication selection before pregnancy remains important even when high-quality prenatal screening is available.
Valproate during an established pregnancy
Valproate exposure during pregnancy carries substantial congenital and neurodevelopmental risks.
However, someone who discovers they are pregnant while taking valproate should not stop it abruptly. Urgent specialist review is needed to consider seizure risk, treatment history and whether a change is safe.
See Valproate and Reproductive Safety for the dedicated page.
Topiramate during an established pregnancy
In the UK, topiramate should not be used for epilepsy during pregnancy unless there is no suitable alternative.
If pregnancy occurs while topiramate is being used for epilepsy, urgent specialist review is required. It should not simply be stopped suddenly because seizure recurrence may be dangerous.
See Topiramate and Reproductive Safety.
Lamotrigine and levetiracetam are among the better-studied options
Current MHRA reviews identify lamotrigine and levetiracetam as among the better-studied antiseizure medicines with comparatively lower risks of major congenital malformation.
This does not mean they are risk-free or suitable for every epilepsy syndrome. Their pregnancy pharmacokinetics also mean dose monitoring can become important.
Newer antiseizure medicines often have less pregnancy data
Absence of a known risk is not the same as evidence of safety.
For several newer antiseizure medicines, pregnancy-exposure numbers are still relatively small. Counselling should distinguish “no signal identified” from “well proven to be low risk”.
Changing treatment after conception is complicated
Switching antiseizure medicine during pregnancy can expose the fetus to both the original and replacement medicines while also risking breakthrough seizures during the transition.
For this reason, major medication changes are ideally completed before conception where possible.
Once pregnancy has begun, the balance becomes highly individual and specialist led.
Folic acid should continue according to the plan
Folic acid started before conception is normally continued through the first 12 weeks in line with current national guidance.
It should not be viewed as a substitute for appropriate antiseizure medicine selection.
See Preconception Planning, Folic Acid and Epilepsy.
Do ordinary pregnancy medicines interact with epilepsy treatment?
They can. Antiemetics, antibiotics, pain medicines, psychiatric medicines and supplements can have their own interactions or neurological effects.
Any new prescription or over-the-counter medicine should therefore be checked against the antiseizure regimen.
Labour and delivery
Epilepsy itself is not normally an indication for caesarean birth. Most people with epilepsy can have a vaginal delivery.
The birth plan should include uninterrupted antiseizure medication, avoidance of prolonged sleep deprivation where possible, access to rescue treatment if required and clear documentation of the usual seizure pattern.
Medication should not be missed during labour
Long labour, nausea, fasting or operative procedures can interfere with usual medication timing.
The maternity team should know the normal antiseizure schedule and have a plan if oral medication cannot be taken.
Pain relief is individual
Most standard obstetric pain-relief options can be considered, but the maternity and anaesthetic teams need the complete medication list and seizure history.
The safest choice depends on the clinical situation, other medicines and any obstetric complications.
The third trimester is also a planning period
By late pregnancy, the epilepsy and maternity teams should be thinking ahead to labour, medication timing, rescue plans, breastfeeding and postpartum dose reduction.
This matters because drug clearance can change quickly after delivery.
The postpartum dose plan should be made before birth
If doses of medicines such as lamotrigine or levetiracetam have been increased during pregnancy, continuing the full pregnancy dose after delivery may cause concentrations to rise as pregnancy-related clearance changes reverse.
NICE recommends making an antenatal plan to begin returning antiseizure medicines toward preconception doses in the first few days after birth when doses were changed during pregnancy.
Postpartum seizure risk is not only about drug levels
Sleep deprivation, missed doses, physical recovery, pain, stress and disrupted routines can all affect seizure control after birth.
The postpartum plan therefore needs to combine medication adjustment with practical support and protected sleep.
Breastfeeding can usually be considered
Most commonly used antiseizure medicines are compatible with breastfeeding with medicine-specific monitoring.
Pregnancy risk should not automatically be copied across to lactation risk because exposure through breast milk is pharmacologically different from exposure through the placenta.
See Breastfeeding and Antiseizure Medicines.
Questions worth asking during pregnancy
- How often should my epilepsy be reviewed during pregnancy?
- Does my antiseizure medicine commonly fall in concentration during pregnancy?
- Do I need blood-level monitoring?
- What is my individual target concentration?
- What should I do if I vomit a dose?
- Who should I contact if seizures increase?
- What symptoms would mean I need emergency maternity assessment?
- Will I need extra fetal growth scans?
- What is the plan for my medication during labour?
- If my dose has increased, when will it be reduced after birth?
The central message
Pregnancy with epilepsy is not simply a matter of continuing the same prescription and waiting until delivery.
Some antiseizure medicine concentrations can fall substantially, particularly with medicines such as lamotrigine and levetiracetam, and seizure control can change. Monitoring should be individualised and interpreted against the person’s own pre-pregnancy seizure control and drug concentration where available.
At the same time, most people with epilepsy can have a normal obstetric pathway, including vaginal birth and breastfeeding. The key is coordinated specialist care, uninterrupted seizure treatment, prompt review when seizures change and a postpartum medication plan made before the baby is born.
Related pages: Hormones, Contraception & Pregnancy · Preconception Planning, Folic Acid and Epilepsy · Valproate and Reproductive Safety · Topiramate and Reproductive Safety · Breastfeeding and Antiseizure Medicines · Seizure Diaries and Recording Seizures
Sources and further reading
NICE NG217 — Principles of treatment, safety, monitoring and withdrawal
ILAE — Management of epilepsy in pregnancy
ILAE — Antiseizure drug clearances during pregnancy and clinical implications
MHRA — Antiepileptic drugs in pregnancy: updated advice following comprehensive safety review
MHRA — Epilepsy medicines and pregnancy: patient safety information
Evidence checked: September 2026.