Ask an obstetrician what abnormal fetal movement means, and the answer is usually about too little of it. Reduced movement is the classic warning sign, the one linked to fetal akinesia and the joint contractures of arthrogryposis.
There is a rarer and stranger pattern at the other end of the spectrum: a fetus having seizures in utero. And according to a review of every case reported in the medical literature, the person most likely to notice is the mother.
Researchers combing PubMed, Google Scholar, and SCOPUS identified 23 publications describing a total of 29 patients with fetal seizures, spanning 1960 to 2024. In 20 of those 29 cases (69%), the seizures were clinically perceived by the mother. Ultrasound detected them in 17 of 29 (58.6%). The review was published in Epilepsy Research.
What Mothers Were Feeling
The movements are not ordinary fetal activity. Reported descriptions involve unusual rhythmic, repetitive movements that women recognized as different from anything else in the pregnancy, and persistent enough to prompt medical evaluation.
Timing differed by detection method. When mothers felt the seizures, gestational age ranged from 20 to 40 weeks, averaging 31.3 weeks. When ultrasound picked them up, the range was wider and started earlier, from 13 to 41 weeks, with an average of 29.3 weeks. When it was applied, imaging tended to catch the problem slightly sooner.
That gap matters less than the raw counts. Ultrasound only finds what someone looks for. In most of these cases, maternal perception was the reason anyone looked at all.
Two Causes Tied for the Top, and One of Them Is Treatable
Fetal seizure causes are heterogeneous, but the review found a clear pair at the top of the list. Pyridoxine-dependent epilepsy and arthrogryposis multiplex congenita each accounted for 4 of 29 cases (13.8%). Fatal infantile olivopontocerebellar hypoplasia accounted for 3 (10.3%).
Pyridoxine-dependent epilepsy is the outlier in that group, because it responds to a vitamin.
It is a rare autosomal recessive disorder in which seizures do not respond to standard antiseizure medications but are controlled by pyridoxine, a form of vitamin B6. Onset is classically within the first month of life and often within hours of birth, but the clinical spectrum is broad and can begin during pregnancy with abnormal fetal movements. The diagnosis is easy to miss precisely because the presentation can mimic common neonatal problems. A case report from Karolinska University Hospital describes a newborn boy initially diagnosed with respiratory distress, birth asphyxia, and persistent pulmonary hypertension who deteriorated and died about 15 hours after birth. Genetic testing after death confirmed the disorder. Consensus guidelines for this condition now exist, and clinical protocols set a low threshold for a pyridoxine trial in resistant neonatal seizures.
Arthrogryposis multiplex congenita sits at the opposite pole of the movement spectrum. It affects roughly 1 in 3,000 to 5,000 live births and is defined by multiple congenital joint contractures. Its shared mechanism, described in a comprehensive review in the journal Genes, is fetal akinesia: sustained reduction in fetal movement that can stem from central nervous system malformations, motor neuron disease, neuropathies, neuromuscular junction defects, congenital myopathies, muscular dystrophies, metabolic disease, or external factors including uterine constraint, maternal illness, and infection. The single most common cause, amyoplasia, accounts for about a third of cases.
Both extremes point in the same direction. How a fetus moves is one of the earliest observable readouts of its nervous system's function.
The Prognosis Is Sobering
The review does not deliver reassurance. Most patients had severe outcomes, including neonatal death or significant developmental delay. That reflects the underlying conditions rather than the seizures themselves, and it reflects who ends up in the published literature, which skews toward the dramatic and the fatal.
The authors describe fetal seizures as underestimated and underdiagnosed events with a poor prognosis that may precede neonatal seizures. They call for registries, prospective studies, and multidisciplinary collaboration to build actual diagnostic guidelines, because none currently exist.
Distinguishing true fetal seizure activity from other abnormal or hyperkinetic fetal movements remains a major practical challenge. Standardized assessment of fetal behavioral states on ultrasound could improve accuracy, but such protocols are rarely reported.
What This Means for an Ordinary Pregnancy
The numbers here should be read carefully. Twenty-nine patients across 23 publications, spanning more than six decades, is not an incidence estimate. It is a count of everything anyone bothered to write up. Fetal seizures are rare enough that most obstetricians will never manage a case.
Normal fetal movement varies enormously. Babies have active and quiet cycles, hiccups that feel rhythmic, and stretches of stillness that mean nothing at all. None of that is what this review describes.
What it does support is a low threshold for saying something. Existing guidance already tells pregnant women to report a change in fetal movement pattern, and that advice is usually framed around decreased movement. This literature suggests that the same instinct applies to movement that is repetitive, forceful, and unlike anything else during pregnancy.
Anyone who notices a change in fetal movement, in either direction, should contact their obstetric provider rather than waiting for a scheduled appointment. It is far more likely to be nothing than something. But in this small and difficult body of cases, maternal perception was the most common route to detection, and in at least one recurring cause, early detection opens the door to effective treatment.
Key Questions Answered
Can a fetus have seizures before birth?
Yes, though it is rare. The review identified 29 patients described in 23 publications, most of which were individual case reports.
How were they usually detected?
Mothers perceived the movements in 20 of 29 cases (69%). Ultrasound detected them in 17 of 29 (58.6%). The two methods overlapped in some cases.
What do the movements feel like?
Reported cases describe unusual rhythmic, repetitive movement that women recognized as distinctly different from normal fetal activity.
What causes fetal seizures?
Causes are heterogeneous. Pyridoxine-dependent epilepsy and arthrogryposis multiplex congenita were the most frequent, each in 13.8% of cases.
Is any cause treatable?
Pyridoxine-dependent epilepsy responds to vitamin B6 rather than standard antiseizure medications, which is why early recognition matters.
When should a pregnant person call their provider?
For any noticeable change in fetal movement pattern, including movement that seems repetitive, forceful, and unlike the rest of the pregnancy.
