Children with autism spectrum disorder (ASD) were more than twice as likely to have been exposed in utero to preeclampsia, and the likelihood of an autism diagnosis was even greater if the mother experienced more severe disease.
Women with preeclampsia experience hypertension during the latter half of their pregnancies, and may have increased levels of protein in their urine and edema, or fluid retention. Preeclampsia can develop into eclampsia, a life-threatening condition in which seizures may occur.
Published in JAMA Pediatrics, the study included more than 1,000 children between the ages of two and three years enrolled in the Childhood Risks of Autism from Genetics and the Environment (CHARGE) Study in Northern California.
“We found significant associations between preeclampsia and ASD that increased with severity. We also observed a significant association between severe preeclampsia and developmental delay,” says Cheryl Walker, assistant research professor in the obstetrics and gynecology department at University of California, Davis.
While preeclampsia has previously been examined as a risk factor for autism, findings have been inconsistent. The current study provides a population-based, case-controlled examination of the association between autism and preeclampsia and whether risk is associated with preeclampsia severity.
The research was conducted in more than 500 male and female children diagnosed with autism; nearly 200 diagnosed with developmental delay; and 350 children who were developing typically. All of the mothers had confirmed diagnoses of preeclampsia.
The mothers of children with autism were more than twice as likely to have had pregnancies complicated by preeclampsia. Mothers of children with autism and children with developmental delay also were significantly more likely to have had placental insufficiency, severe preeclampsia, or both, when compared to the mothers of children who were developing typically. The children with autism of mothers with preeclampsia also were more likely to be cognitively lower functioning.
There was also a correlation between preeclampsia and developmental delay without autism, primarily in instances involving placental insufficiency.
There are several mechanisms by which preeclampsia may affect the developing brain, Walker says.
For the fetus, limitations in nutrient and oxygen availability cause progressive oxidative stress which prompt the release of proteins into the maternal bloodstream in an effort to improve circulation.
“The level of detail obtained by the CHARGE Study on predictors, confounders, and outcomes enabled a comprehensive exploration of this topic,” Walker says. “While single studies cannot establish causality, the cumulative evidence supports efforts to reduce preeclampsia and diminish severity, to improve neonatal outcomes.”
The National Institute of Environmental Health Sciences, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the US Environmental Protection Agency through Science to Achieve Results, and the UC Davis MIND Institute funded the study.
Source: UC Davis