Here’s what experts say about the link between maternal infections and an increased chance of autism in children.
ADVERTISEMENTOur understanding of autism has evolved significantly since the term was first coined in 1911, with autism spectrum disorder (ASD) now usually seen not as an “illness” or “disease”, according to the UK’s NHS, but as a set of traits. which vary greatly in type and weight.
Yet despite these advances, scientists are still struggling to understand many aspects of the condition.
These include underlying causes that contribute to or increase the likelihood of autism, although current research primarily points to a combination of genetic and environmental factors.
One such factor is infection during pregnancy, such as influenza, which has been the focus of extensive studies in both animal models and humans.
Although this link is not necessarily causal, meaning that catching the flu during pregnancy does not guarantee that a child will develop autism, research suggests that such infections could be a contributing factor.
Does getting the flu during pregnancy lead to autism?
“Our work suggests that women who have febrile episodes, who have high titers of antibodies rising to herpes simplex type 2, who report influenza and have documentation of influenza are at greater risk of having children subsequently diagnosed with ASD,” Dr Ian Lipkin, director of Columbia University’s Center for Infection and Immunity, told Euronews Health.
Lipkin was the senior author of a study investigating a potential link between getting the flu during pregnancy and the risk of autism in children.
The study focused on laboratory-confirmed cases of influenza, rather than relying solely on survey responses or medical records, and found some evidence of an increased risk of ASD when laboratory-diagnosed influenza was accompanied by severe self-reported symptoms.
“None of this is terribly surprising,” Lipkin said.
“I mean, we tell women not to drink during pregnancy, not to take certain medications during pregnancy, not to smoke during pregnancy, so why should we be surprised that another environmental factor might not also be important in causing normal fetal development.
The authors said that if infections contribute to the increased risk of autism, it may not be because of the virus itself, but rather the response of the mother’s immune system and the inflammation it causes.
Why can viral infections in pregnancy lead to autism?
To better understand what happens to the fetus when the mother gets an infection that leads to autism, researchers studied animal models.
Dr Irene Sanchez Martin, who is a postdoctoral researcher at Cold Spring Harbor Laboratory in the US, recently presented findings from her ongoing animal study examining how inflammation during pregnancy may contribute to neurodevelopmental disorders in children.
Her research, she told Euronews Health, was done in mouse models and found that maternal immune activation (MIA) during pregnancy is associated with behavioral outcomes similar to what might translate to autism in humans.
“We can’t say that the mouse has autism because it’s a different syndrome, but they can replace some behavior, abnormalities, that can be associated with neurodevelopmental disorders, which are usually autism and schizophrenia,” she explained.
ADVERTISEMENTThe research also focused on studying the immediate effects of exposing pregnant mice to the viruses, which Sanchez Martin said could be roughly equivalent to the first trimester in humans.
It has been shown that after the mother’s immune system is activated following a simulated infection, there are early signs of developmental deficits in the embryos even within 24 hours of exposure.
It is interesting that developmental deficits were mostly present in male embryos and not in female ones, she said.
‘Inflammation, not a specific cause of infection’
While Sánchez Martin emphasized that these results may not fully translate to humans due to the use of mouse models, she added that they may shed light on components that help explain the factors that lead to autism, given that mouse studies allow comparison between embryos from the same mother.
ADVERTISEMENTThe findings were that disturbances in the fetal environment such as amniotic fluid or the placenta could explain why some were at higher risk of developmental abnormalities.
“Basically, this makes us realize that inflammation is a factor that is associated with these problems,” said Sanchez Martin.
Lipkin also added that “elevated levels of cytokines associated with inflammation” are common in women who have children who are subsequently diagnosed with autism.
“So we think it’s inflammation, not a specific infectious agent, and there’s a lot of ways it can be triggered,” he said.
ADVERTISEMENT