A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Fall, 2022 | Number 4, Volume 36

Link between maternal infection, autism in children questioned

While maternal infections during pregnancy are associated with an increased risk of autism spectrum disorders (ASD) in children, a new study suggests that this may not be due to the effects of the infections themselves. 

Martin Brynge and colleagues analyzed data from nearly 550,000 children in Stockholm, Sweden. Approximately 34,000 of the children’s mothers had documented evidence of an infection during pregnancy requiring specialized health care. 

Consistent with earlier studies, the researchers found that children exposed to infections in utero had a higher likelihood of receiving an autism diagnosis, as well as an increased risk of being diagnosed with intellectual disability. However, they found that maternal infections occurring in the year prior to pregnancy were associated with autism as well—a finding that casts doubt on the theory that the infections that occurred during pregnancy were the cause of autism. 

In addition, the researchers analyzed data from nearly 400,000 children in the study group who had full siblings. They found that siblings exposed to maternal infections were not at higher risk for autism compared to their unexposed siblings. 

The researchers conclude, “Although infections in pregnant women are associated with both autism and intellectual disability in their children, the association with autism does not appear to reflect a causal relationship, but is more likely to be explained by factors shared between family members such as genetic variation or aspects of the shared environment. Thus, infection prevention is not expected to reduce autism incidence.” 

The researchers note, however, that their findings apply only to infections in general and not to specific viruses—for example, rubella and cytomegalovirus—that are firmly linked to an increased risk for autism and other developmental disabilities. They also note that their data could not rule out a causal link between maternal infection during pregnancy and intellectual disability.


Citations

“Maternal infection during pregnancy and likelihood of autism and intellectual disability in children in Sweden: a negative control and sibling comparison,” Martin Brynge, Hugo Sjöqvist, Renee M. Gardner, Brian K. Lee, Christina Dalman, and Håkan Karlsson, The Lancet Psychiatry, Vol. 9, No. 10, pp. 782-791, October 1, 2022. Address: Martin Brynge, [email protected]

—and—

 “Registry review casts doubt on causal link between maternal infection and autism,” Charles Q. Choi, Spectrum News, September 23, 2022. 

—and—

 “New knowledge about the link between infection during pregnancy and autism,” news release, Karolinska Institutet, September 7, 2022