New insight into autism and infections in pregnancy 

New insight into autism and infections in pregnancy 
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Research illuminates new knowledge about infections in pregnancy and the increased risk of neurodevelopmental conditions. 

Having an infection in pregnancy can be detrimental to your unborn child. Common infections can cause adverse effects like miscarriage and neurodevelopmental conditions. However, the Karolinska Institutet unearthed new information about the link between autism and infections in pregnancy. 

“Our results can reassure expectant parents by indicating that infections during pregnancy may not pose as great a risk to the baby’s brain as previously thought,” said Håkan Karlsson, a researcher at the Department of Neuroscience at Karolinska Institutet and the study’s senior author. 

The research is published in The Lancet Psychiatry. 

Is an infection the cause behind autism in children? 

Previous studies have illuminated a connection between infections in pregnancy and an increased risk of neurodevelopmental conditions such as autism or intellectual disabilities in children. Despite this link, research has not confirmed whether infection exposure is the cause or whether other factors have an impact. This drove the researchers from Karolinska Institutet have studied this in more detail. 

The study is based on over 500,000 children born between 1987 and 2010. The goal was to understand if there is a causal relationship between infections in pregnancy and autism or intellectual disability in the child. The infections were included if they are severe enough to require specialist care, and they were identified using diagnostic codes from patient and birth records. 

The researcher’s results were similar to previous studies where infections leading to specialist care did link to increased risk of autism and intellectual disability in children. However, when the researchers studied siblings, the results were different. In comparison between the siblings where there was an infection in one pregnancy but not the other, they could not find a link between infection and autism risk. Moreover, the risk of intellectual disability was even lower. 

Infections in pregnancy and autism are not causal 

The research revealed that infections in the year before pregnancy were linked to the risk of autism to the same degree as infections in pregnancy but not linked to the risk of intellectual disability. 

“The link between infections in pregnant women and the increased risk of autism in their children does not appear to be causal. 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,” said Martin Brynge, PhD student at the Department of Global Public Health, Karolinska Institutet, and one of the study’s two first authors. 

The results were less clear for intellectual disability, but it cannot be ruled out that infections in pregnancy may affect children’s risk of disability. In any case, infections during pregnancy may not influence the risk of intellectual disability to the same extent as previously thought, according to the researchers. 

The researchers emphasise that they have only focussed on the diagnosis of infections in general. The study does not contradict the significance of the proven links between some specific viral infections in pregnancy, such as cytomegalovirus infection and rubella, and the serious implications on the child. The researchers also noted that infections caused by COVID-19 were not included in the study. 


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