Fevers Linked to Autism Risk
Having a fever in the second trimester may increase the risk of autism.
A new prospective cohort study from Norway found that mothers who had a fever during the second trimester of pregnancy had a roughly 40% higher chance of having a child with autism.
Fevers in the first and third trimesters had little to no effect. This is consistent with the fact that fetuses go through stages of development. As the brain develops, they are most vulnerable to external risks at specific periods.
Previous studies had found evidence that infection and fever may play a role in autism risk. This is one of the first large-scale studies to provide statistical evidence of this effect.
How the Fever-Autism Link Works
Researchers believe that this may be caused by inflammatory compounds released by the immune system.
When the body encounters viruses and bacteria, white blood cells release inflammatory molecules that signal the presence of potential germs. Since the mother and the fetus share a blood supply, these molecules can potentially affect the fetus if an infection happens during a particularly critical development period.
Autism Spectrum Disorder
The Key Deficits in Autism Spectrum Disorder
Multiple fevers are linked to a higher risk of autism
The risk of autism goes up with the number of fevers a mother has after 12 weeks. Having 1-2 fevers was associated with a small increase in risk. Having three or more fevers was associated with around triple the risk of autism.
Given that this research is so new, there are still many unanswered questions about this effect. The most important unanswered question is whether this effect is causal. Do fevers actually cause autism or are they only correlated with something else that does?
These data point to a potentially concerning link. However, we will need more research before we know this for sure and before we know how to fully prevent this. In the meantime, here are two common-sense tips that we would recommend:
Our recommendations: 1-Take a Tylenol when you have a fever: There is some evidence that taking medication to reduce fever may reduce this effect.
2-Keep healthy: Reduce your stress, stay hydrated, and stay healthy. Whether fevers affect autism or not, self-care is always going to be a good thing.
Autism + Fever Study
Number of Patients
Fevers during pregnancy