Gestational Eclampsia Linked to Fivefold Epilepsy Risk

Gestational hypertension, preeclampsia, or eclampsia is associated with a significantly higher risk for neurologic disorders such as migraine or epilepsy in the years following a first pregnancy, new research suggests.

The risk was highest in those with gestational eclampsia, who had a 70% increased chance of developing a neurologic disorder, including a fivefold increased risk for epilepsy, investigators found.

“When consulting women with new-onset neurological disorders, it’s important to inquire about their pregnancy history, as pregnancy complications such as gestational hypertension, preeclampsia, and eclampsia have been associated with an increased risk of neurological disorders later in life.” Therese Friis, MD, PhD student, Department of Women’s and Children’s Health, Uppsala University, Uppsala, Sweden, told Medscape Medical News.

The findings were published online on December 23 in JAMA Neurology.

Most studies of maternal outcomes after gestational hypertension, preeclampsia, or eclampsia have focused on long-term risks for cardiovascular disease or neurologic complications such as stroke, dementia, and cognitive impairment. And many of these studies were relatively small and based on interviews or questionnaires.

“We wanted to investigate whether women with a hypertensive disorder of pregnancy also had a risk of other neurological complications, closer in time to the pregnancy,” said Friis.

The new study included 648,385 women (mean age, 28.5 years) whose first pregnancy occurred between 2005 and 2018. Of these, 94% had a normotensive pregnancy, 2% had gestational hypertension, 4% had preeclampsia without eclampsia, and 0.1% had eclampsia.

Gestational hypertension was defined as new-onset systolic blood pressure of ≥ 140 mm Hg and/or diastolic blood pressure ≥ 90 mm Hg; preeclampsia was defined as gestational hypertension accompanied by proteinuria; and eclampsia was defined as tonic-clonic seizures without other etiology accompanied by preeclampsia.

Researchers used linked Swedish national registries that collect data on pregnancies, births, and infant and maternal characteristics. Among other things, they controlled for maternal age, early pregnancy body mass index, education level, and pregestational and gestational diabetes.

The primary outcome was a composite of five new-onset neurologic diagnoses: Migraine, headache, epilepsy, sleep disorder, and mental fatigue (neurasthenia), although one diagnosis was sufficient, from 42 days to 15 years after childbirth. Mean follow-up was 7.7 years.

Fivefold Epilepsy Risk

Compared with normotensive pregnancies, the risk for the primary outcome was 70% greater in those with eclampsia (adjusted hazard ratio [aHR], 1.70; 95% CI, 1.16-2.50), 27% higher for gestational hypertension (aHR, 1.27; 95% CI, 1.12-1.45), and 32% for preeclampsia (aHR, 1.32; 95% CI, 1.22-1.42).

Researchers also looked at the risk for individual neurologic disorders. There were too few neurasthenia events to generate meaningful results, so this diagnosis was omitted from the analysis.

Here, the study found women with eclampsia had five times the risk for epilepsy (aHR, 5.31; 95% CI, 2.85-9.89) compared with women with normotensive pregnancies.

The underlying mechanism for this association is unclear. However, said Friis, eclampsia and epilepsy share common pathways, such as neuroinflammation, and women with epilepsy before pregnancy run an increased risk for eclampsia.

“So common underlying pathways might increase the risk both for eclampsia in cases of a seizure disorder and a future seizure disorder after eclampsia,” she said.

In addition, preeclampsia and, in particular, eclampsia can cause irreversible subclinical cerebral infarcts found in areas of cerebral edema, she added. “These infarcts or scarring of brain tissue could potentially serve as foci for later epileptic activity.”

Researchers separated women with preeclampsia (with or without eclampsia) into those with preterm (less than 37 weeks; 21%) and term (79%) deliveries. As Friis explained, women with preterm preeclampsia have a higher risk for acute complications and long-term cardiovascular outcomes than those with term preeclampsia.

Compared with those with normotensive pregnancies, investigators found an increased risk for the composite neurologic outcome among women with preterm preeclampsia (aHR, 1.54; 95% CI, 1.34-1.79), but also for those with term preeclampsia (aHR, 1.27; 95% CI, 1.17-1.38).

Common Vascular Component

The study also showed gestational hypertension and preeclampsia were associated with a later diagnosis of migraine, suggesting a possible common underlying vascular component.

“The increased risk of migraine following preeclampsia could be linked to endothelial damage at the blood-brain barrier level and alterations in cerebral blood flow and arterial vasospasm found in eclampsia, but this is only speculation,” said Friis.

The analysis also found an association between preeclampsia and a later diagnosis of headache. But this result likely encompasses several headache diagnoses, including migraine, so “it’s challenging to draw conclusions about the underlying mechanisms,” Friis added.

The study didn’t consider diagnoses from primary healthcare, which resulted in relatively few outcomes. The authors explained they could only identify the most severe cases; for example, women referred to specialized care.

Another potential study limitation is that Swedish registers don’t include information on race or ethnicity. Evidence shows there are racial differences in the risk for cardiovascular outcomes after preeclampsia.

This area of research is important as most women will experience at least one pregnancy in their lifetime, and preeclampsia affects 3%-5% of pregnancies. Further research is needed to understand the underlying pathophysiological mechanisms and the long-term consequences of this disorder, said Friis.

She added she hopes more therapeutic options will be available in the future for neuroprotective treatment for women with gestational hypertensive disorders.

Asked to comment, Thomas Vidic, MD, clinical professor of neurology, Indiana University School of Medicine, South Bend, Indiana, told Medscape Medical News this is an important study that includes robust data.

In his opinion, the most significant study finding is the marked increase in epilepsy risk after gestational eclampsia.

“In women who have new-onset epilepsy of unknown cause, asking about having eclampsia or preeclampsia during pregnancy is definitely a worthwhile question,” he said.

Confirming an etiology paints “a better picture” for patients wondering why they’re experiencing seizures, he added.

As with any registry-based study, this one had some acknowledged limitations, “but at the same time, the authors were able to have such a large database that I think this study is very worthwhile,” said Vidic.

The study received support from the Swedish Research Council. Friis had no relevant conflicts of interest. Vidic had no relevant conflicts of interest.