Although, Researchers Maintain the Association Is Not Causal
The Karolinska Institutet in Stockholm recently released a study that found that maternal infection during pregnancy is associated with autism and intellectual disability in offspring. However, this association does not appear to be causal. The team behind this work analyzed data from children living in Stockholm born between 1987 and 2010. In total, the study included 549,967 children. The researchers specifically investigated the associations between maternal infection during pregnancy and these offspring’s risk for autism and intellectual disability. The team also examined the possibility of a causal role within these associations. After analyzing the data, the researchers discovered that 1.3% and 3.3.% of the 34,013 children exposed to maternal infection during pregnancy were later diagnosed with intellectual disability and autism, respectively. Of the 515,954 unexposed children, 1.0% and 2.5% were diagnosed with intellectual disability and autism, respectively. The higher percentages in the infection-exposed cohort demonstrate that exposure to maternal infection during pregnancy is associated with autism and intellectual disability. Additionally, this work discovered an association between maternal infection in the year before pregnancy for autism but not intellectual disability. A sibling comparison (without autism) was also conducted, which found a lower association between maternal infection during pregnancy with autism and, to a lesser extent with intellectual disability. In the end, after the researchers adjusted for pre-pregnancy infection or infection while pregnant with a sibling without autism, the association grew weaker and, therefore, could not be considered causal. Martin Brynge, Ph.D., one of the study’s two first authors, added more context to these findings. He states, “The link between infections in pregnant women and the increased risk of autism in their children does not appear to be casual. Our results suggest that the increase in risk is more likely to be explained by factors common between family members, such as genetic variation or certain aspects of the shared environment.”
