When you’re pregnant, a million questions can run through your mind about your baby’s health as they grow. You may have questions about the risk of seizures happening to your baby in utero, especially if you live with epilepsy yourself.

Many neurological conditions can start in the womb, including epilepsy and many developmental disorders. While very rare, fetal seizures may be an early warning sign.

In this article, we’ll discuss fetal seizures, how often they occur, and what they might mean for your baby’s health.

How Rare Are Seizures in the Womb?

Seizures in the womb are extremely rare, with only 29 confirmed cases between 1960 and 2024.

With so few known cases, it’s possible that seizures are underdiagnosed or underreported. Some pregnant mothers might not realize what’s happening. When seizures do occur, they often point to serious health issues, and they’re usually diagnosed with ultrasound rather than just based on what the mother perceives.

If you feel unusual fetal movement, it might have a harmless cause such as a baby’s hiccups in the womb. It may also be related to a neuromuscular disorder or some other condition rather than a seizure.

Ultrasound imaging might make it easier for obstetricians to recognize when a seizure has occurred in the womb. However, because fetal seizures are so rare and understudied, ultrasound isn’t foolproof either.

Experts are researching ways to make detecting and diagnosing fetal seizures easier.

How Fetal Seizures Are Detected

There are two known ways of detecting whether a fetal seizure has occurred: self-reported signs felt by the mother and ultrasound imaging tests.

Early diagnosis of a baby’s neurological problem might make it easier for you or your obstetrician to know when a fetal seizure happens and start anti-seizure treatment soon after the baby is born.

Seizures Felt By the Mother

Babies move around in the womb in different ways, with some babies moving a lot more than others. As you go through your pregnancy, you develop an idea of how much movement is “normal” for your baby. You should always contact a doctor about any change in your baby’s movement patterns, even if you don’t immediately assume it’s a seizure.

In the literature review of the 29 known cases of fetal seizures, mothers felt a change in their babies’ movement in 20 of the 29 cases.

In most cases, the mothers felt large movements associated with tonic-clonic seizures. These include periodic and rhythmic jerking. Rarely, the movements felt more subtle or were barely felt at all.

When the seizures were felt by the mother, they typically occurred between weeks 20 and 40 of the pregnancy. On average, they happened at 31.3 weeks, which is in the third trimester of pregnancy.

Detected by an Ultrasound

Ultrasound imaging is a common scan used during pregnancy to monitor a baby’s growth. It’s safe for the mother and the baby because it doesn’t use radiation to produce an image — it uses sound waves instead.

Of the 29 cases studied in the literature review, 17 of the fetal seizures were detectable on an ultrasound. Those detected with an ultrasound were usually found earlier.

Ultrasound detection ranged from 13 to 41 weeks. On average, they happened at 29.3 weeks. This is still in the third trimester, but some cases were found earlier.

According to this research, ultrasound imaging may allow for earlier detection of seizures in the womb. Early detection with ultrasound could allow for more effective management while the baby is still in utero and after they’re born.

Possible Causes of Fetal Seizures

While research is still lacking about fetal seizures and what causes them, experts believe seizures in utero can have many possible causes. They almost always indicate that the baby will have neurological complications after being born. Here are some of the most commonly suspected causes:

Central Nervous System Problems

The CNS consists of the spinal cord and brain, which is where seizures start. Experts believe that many in utero seizures happen due to congenital (before birth) abnormalities in the CNS, including:

• Loss of nerve cells in the brain
• Too much fluid in the brain
• Poor formation of brain wrinkles

Early-Onset Epileptic Encephalopathies

Early-onset epileptic encephalopathy may also cause fetal seizures.

Epileptic encephalopathies are severe forms of epilepsy that significantly reduce brain function. While they typically first appear in babies and children who are already born, they may cause fetal seizures if they develop early while the baby is still in the womb.

Peripheral Nervous System Disorders

Experts believe that some fetal seizures may be caused by disorders of the peripheral nervous system (PNS), which includes all of the nerves in the body outside of the brain and spinal cord. It’s possible that some seizures in utero may come from PNS disorders like muscular dystrophy.

What Fetal Seizures Can Mean for the Baby’s Health

Usually, fetal seizures are a sign of a poor prognosis for the baby. This means that the baby’s health may decline in the womb, or the baby may have medical conditions once they’re born.

What happens to a baby who has had seizures in the womb usually depends on the underlying cause of the seizures. Not every case is predictable.

Some babies may die before they’re born or shortly after they’re born. Others may be born with neurological conditions that affect them for the rest of their lives.

Babies who survive childbirth may have complications beyond CNS or PNS conditions. Possible complications include respiratory, cardiovascular, metabolic, hematologic, infectious, gastrointestinal, and musculoskeletal problems.

Psychomotor Delays

Psychomotor problems involve slowed thinking and speech and less movement.

Developmental delays might become more apparent as the baby grows, as they may miss expected developmental milestones.

Hypotonia

Hypotonia, which is also called floppy infant syndrome, is a condition in babies characterized by poor muscle tone and resistance. Babies with hypotonia may feel limp when you hold them. They may also have a weak cry, have trouble swallowing or sucking, and lack control over their neck and other muscles as they grow.

Talk to Your Doctor

It’s important to work closely with your obstetrician as you go through your pregnancy. If you have epilepsy yourself, your doctor can tell you more about the risk of epilepsy in your baby. Your epilepsy may increase the risk of fetal seizures, but keep in mind that fetal seizures are exceedingly rare.

If you have epilepsy or are concerned about your baby’s risk of epilepsy, ask your doctor about steps you can take to support your baby’s health and development. Be sure to attend all of your fetal monitoring visits and follow all instructions on pregnancy care from your doctor.

Your obstetrician, your neurologist, and the rest of your healthcare team can work together to help you navigate epilepsy as you become a parent.

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