Epilepsy is one of the most common neurological diseases, and researchers are still trying to figure out its many effects.

People with epilepsy are at a higher risk of dying than the general public, and epilepsy is associated with everything from psychological conditions to physical injuries. A study in Obstetrics & Gynecology suggests severe outcomes during and after childbirth should be added to the list. It found that people with epilepsy are up to three times more likely to experience such outcomes than those without the disease.

Researchers examined birth certificate and hospital discharge data for over 2.6 million people in California between 2007 and 2012. About 8,000, or about 0.3 percent, were of patients with epilepsy.

Twenty-five percent more of them had Caesarean sections than people without epilepsy, and twice as many had severe preeclampsia. About 13 percent gave birth preterm, the majority before 34 weeks, a 70 percent increase compared to those without epilepsy.

The risk of severe maternal morbidity — serious problems such as needing blood transfusions, hysterectomies or ventilators — was even steeper. Twice as many people with epilepsy had these outcomes. Blood transfusions are the most common procedure in patients with severe maternal morbidity; patients with epilepsy were three times as likely as those without to experience severe effects outside of transfusions.

Pregnancy can be nerve-racking for those with epilepsy, some of whom must modify the dosage or type of drugs they take to control seizures. But a 2013 study found that two-thirds of them do not have a seizure during pregnancy.

Due to data use agreements, the researchers didn’t report the rates of extremely rare outcomes such as death. But other studies have shown that pregnant patients with epilepsy are up to 11 times more likely to die during pregnancy than those without.

“Reassuringly,” the researchers write, “the absolute risks remain low” for patients with epilepsy. Just over 4 percent experienced severe outcomes. According to the Epilepsy Society, people with epilepsy give birth to about 24,000 babies a year.