Risk of various neurodevelopmental disorders is higher in children of mothers who experienced preeclampsia, according to a study by NIEHS researchers. Preeclampsia is a serious vascular condition that can occur during pregnancy, resulting in high blood pressure.
The study, published April 1 in JAMA Psychiatry, is the most comprehensive examination of the association between preeclampsia and neurodevelopmental disorders in children. For the first time, researchers used data from a large population to provide strong evidence that links the pregnancy complication to a wide range of disorders, including increased risk of epilepsy and intellectual disability.
Wilcox helps to develop epidemiologic tools to study human reproduction and has a secondary appointment in the NIEHS Reproductive and Developmental Biology Laboratory. (Photo courtesy of Steve McCaw)“Preeclampsia is a well-established threat to the mother, but the risks to children are usually regarded as less important, other than the dangers associated with preterm delivery,” said senior study author Allen Wilcox, M.D., Ph.D., emeritus investigator in the NIEHS Epidemiology Branch. “The findings suggest that preeclampsia during full-term pregnancies may have lasting effects on nervous system development in children.”
A puzzling condition
Past research has shown that children of mothers with preeclampsia are more likely to have cerebral palsy — a group of neurological disorders that cause permanent movement problems. Moreover, the pregnancy complication increases the risk that children will develop autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD).
However, it has not been clear whether children of mothers with preeclampsia are also more likely to have other neurodevelopmental disorders, according to study author Quaker Harmon, M.D., Ph.D., a staff scientist in the NIEHS Women’s Health Group. Another major unknown was whether preeclampsia during full-term pregnancies increases risk of neurodevelopmental disorders.
“Because the main treatment for preeclampsia is delivering the fetus, preeclampsia is a leading cause of preterm birth,” Harmon explained. “On its own, preterm birth may lead to cerebral palsy and other neurodevelopmental disorders. The degree to which previous associations between preeclampsia and neurodevelopment were due to preterm birth was unclear. Our finding of this link in full-term pregnancies was unexpected.”
Harmon was named NIEHS Fellow of the Year in 2014. (Photo courtesy of Steve McCaw)Possible effects on brain development
Wilcox and his team collaborated with a Norwegian neonatologist to make use of Norway’s Medical Birth Registry, which is a unique and rich source of information. The dataset consists of 980,560 full-term births between 1991 and 2009. The researchers examined the incidence of neurodevelopmental disorders in children up to five years of age.
Consistent with previous research, they found that preeclampsia was associated with an increased risk of ASD and ADHD. In addition, the study expanded the list of possible effects of the pregnancy complication to include epilepsy and intellectual disability. Previous evidence for these two potential outcomes was insufficient and contradictory, Wilcox said.
One important advantage of the study was that the researchers restricted their analysis to full-term births. As a result, the findings suggested that preeclampsia might have broad effects on brain development, even after excluding the potential role of preterm delivery. However, the incidence of neurodevelopmental disorders was low and not a reason for alarm, Harmon noted.
“That said, preeclampsia during full-term pregnancies is usually a mild condition for the mother, with few health implications for the child after birth,” Harmon added. “Given all this, it was unexpected that preeclampsia, or something closely associated with preeclampsia, during full-term pregnancies could affect brain development across a wide spectrum of outcomes.”
Medical enigma
Building on these findings, the researchers plan to investigate the biological factors underlying the link between preeclampsia and neurodevelopmental disorders. This research could lead to the discovery of prenatal biomarkers that clinicians could use to decide on interventions that may benefit children’s health.
“We're a long way from interventions, but if we know more about the biological conditions that increase the risk of neurodevelopmental problems, we might be able to develop strategies to reduce that risk,” Wilcox said. “Preeclampsia remains a medical enigma, despite many hundreds of published studies on the topic. We are continuing to explore aspects of preeclampsia to try to understand what triggers it and how it affects both the mother and her child.”
Citation: Sun BZ, Moster D, Harmon QE, Wilcox AJ. 2020. Association of preeclampsia in term births with neurodevelopmental disorders in offspring. JAMA Psychiatry; doi: 10.1001/jamapsychiatry.2020.0306.
(Janelle Weaver, Ph.D., is a contract writer for the NIEHS Office of Communications and Public Liaison.)
