Preeclampsia is a condition that appears during pregnancy and is characterized by high blood pressure and protein in the urine. Now, in a new study, researchers have found that children with autism spectrum disorder were more than twice as likely to be born to mothers with preeclampsia during pregnancy, suggesting a link between the two.

The researchers, from the University of California-Davis’ MIND Institute, publish their results in the journal JAMA Pediatrics. They also found that the likelihood of a diagnosis for autism spectrum disorder (ASD) increased further if the mother experienced more severe disease. Preeclampsia typically occurs during middle to late pregnancy and up to six weeks after delivery, though it can sometimes appear earlier than 20 weeks. Symptoms for the condition include swelling, sudden weight gain, headaches and changes in vision.

In the US, preeclampsia affects 3-5 percent of pregnant women, but among women who have had it, around 20-40 percent of their daughters and 11-37 percent of their sisters will also get the disorder, according to the World Health Organization (WHO). Preeclampsia accounts for around 40-60 percent of maternal deaths in developing countries, and it can develop into eclampsia, a life-threatening condition often accompanied by seizures.

According to Cheryl Walker, senior author and researcher from the MIND Institute, preeclampsia can affect the developing brain in several ways. For example, limited nutrients and oxygen can cause oxidative stress, which encourages the release of proteins into the maternal bloodstream in an attempt to improve circulation.