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.

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Preeclampsia appears during middle to late pregnancy and may be accompanied by increased levels of protein in the urine and fluid retention.

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 6 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% of pregnant women, but among women who have had it, around 20-40% of their daughters and 11-37% of their sisters will also get the disorder, according to the World Health Organization (WHO).

Preeclampsia accounts for around 40-60% 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.

Study 'cannot establish causality' but supports efforts to reduce preeclampsia

Fast facts about preeclampsia

  • Preeclampsia typically occurs in first pregnancies
  • Factors such as obesity, carrying more than one fetus and pre-pregnancy high blood pressure or kidney disease can increase a woman's risk for it
  • Preeclampsia is more common among women with histories of certain health conditions, including migraine headaches, diabetes, lupus, gum disease and sickle cell disease.

Learn more about preeclampsia

The latest study involved over 1,000 children, between 2 and 3 years old, who were part of the Childhood Risks of Autism from Genetics and the Environment (CHARGE) Study in Northern California.

Though preeclampsia has previously been studied as an autism risk factor, the researchers say previous research has been inconsistent.

However, theirs is a population-based, case-controlled study that investigates not only links between autism and preeclampsia, but also whether autism risk is associated with preeclampsia severity.

In more than 500 male and female children who were diagnosed with autism, 200 were diagnosed with development delay and 350 were developing typically. All of the mothers of these children had confirmed preeclampsia.

Results showed that mothers of children who were diagnosed with autism were over twice as likely to have had preeclampsia during pregnancy.

Furthermore, mothers of autistic children or those with developmental delay were more likely to have had placental insufficiency, severe preeclampsia or both, compared with the mothers of children who developed typically.

In the video below, Walker discusses the effects of preeclampsia on autism:

She and her team also found that children with autism whose mothers had preeclampsia were more likely to have lower cognitive functioning. Additionally, they observed a correlation between preeclampsia and developmental delay without autism.

Commenting on their findings, Walker says:

"The level of detail obtained by the CHARGE Study on predictors, confounders and outcomes enabled a comprehensive exploration of this topic. While single studies cannot establish causality, the cumulative evidence supports efforts to reduce preeclampsia and diminish severity, to improve neonatal outcomes."

Medical News Today recently reported on a cancer drug currently undergoing testing that may also be effective against some symptoms of fragile X syndrome, an inherited form of autism.