The review, published in 2014 in the Journal of Child Psychology and Psychiatry, examined the results of 13 high-quality studies on long-term outcomes of babies born by caesarean section. After analyzing the data, the researchers found that caesarean deliveries were associated with a “modest increase” in the odds of developing autism spectrum disorders, compared to vaginal deliveries.
However, a very important note to make is that this study did not analyze why many of these women had a C-section. That is, if they needed a C-section because their baby was too big to deliver vaginally or from a mom having poorly controlled diabetes, it could actually be the diabetes that was the cause for the increase in autism rates, not the C-section itself.
The authors also noted that the effect was very small, but given the rapid increase in caesarean deliveries, even a small increase in the number of children with autism could have large effects on society.
Researchers have long searched for an identifiable cause of autism, hoping to explain the rapid increase in the diagnosis of autism spectrum disorders. According to this research group, there are several possible reasons caesarean births might increase a baby’s risk of developing autism.
The leading one, they suggested, had to do with the complex interaction of genetic susceptibility and exposure to the mother’s bacteria and microbes during birth. Many experts believe some children have a genetic predisposition to autism that, when combined with environmental “triggers,” results in the development of autism.
It’s already been established that babies born via caesarean have different gut microbes, or intestinal bacteria, than babies born vaginally (a healthy intestinal tract is colonized by billions of different strains of bacteria that contribute to everything from digestive health to a strong immune system). Similarly, it’s been established that children with autism spectrum disorders have different gut microbe composition than non-autistic children. The researchers speculated that these two might be connected: the children born via caesarean are colonized with a less-than-optimal set of bacteria and microbes from their mother’s skin instead of the birth canal during delivery, with long-term ramifications.
This is but one theory, however, and researchers advanced several others. It’s very important to keep in mind that this study was not able to identify why many of these women had to deliver by C-section, so further research into this may help better identify why these babies have a higher autism risk.
Reviewed by Dr. Jen Lincoln, April 2020
- C-section deliveries were associated with a “modest increase” in the odds of developing autism spectrum disorders, compared to vaginal deliveries.
- Many experts believe some children have a genetic predisposition to autism that, when combined with environmental “triggers,” results in the development of autism.
- Babies born via C-section have different gut microbes than babies born vaginally.