Why is there a link between c-sections and autism?

Happy New Year!  Over the holiday break, a the largest study so far including the most number of countries analyzed the risk of having a c-section and autism.  They found a consistent increase risk that wasn’t due to cause of the c-section or the age of the infant (preemie or term).  So what is going on?  This week’s podcast warns against the unintended consequences of linking c-sections to autism and offers an explanation of the findings in addition to what the study authors provide.

3 thoughts on “Why is there a link between c-sections and autism?

  1. Dr. Halladay,

    Hello, I am an adult on the autism spectrum. I am married to a man also on the spectrum, and we have three children, the oldest of whom is also on the spectrum, the middle is likely part of the broader autism phenotype, and our toddler is just showing mild sensory issues so far.

    I just wanted to comment about your recent podcast about c-sections. I wanted to throw in my theory of what may be causing the link between c-sections and autism. People on the autism spectrum are more than twice as likely to be in a breech presentation (https://www.sciencedaily.com/releases/2009/04/090427091115.htm). And the current trend dictates that breech presentations are almost always delivered by c-section. I myself was breech, but born vaginally, since that was the trend in the 70’s. The breech presentation may be caused by the fact that many people on the autism spectrum have hypotonia. An infant with hypotonia likely wouldn’t be as capable of getting into the head down position and participating in the birthing experience like a typical infant would. However, that is only part of it. The mother may also be on the spectrum or have spectrum traits (even if she isn’t diagnosed and this wasn’t reported or screened for, we know the strong genetic link that exists), and many people on the autism spectrum have hypotonia and hypermobility in their joints. Hypermobility is now almost always referred to as Elhers Danlos, and not Hypermobility Syndrome as it used to be referred to. Many women on the spectrum report having Elhers Danlos. Elhers Danlos can cause many issues in pregnancy and delivery, found here: http://www.medscape.com/viewarticle/520046_4 As you can see, one of those issues is malpresentation, including breech, theorized to be due to hypotonia or Elhers Danlos in the infant. However, hypermobility in the joints of the mother can lead to malpresentation of the infant as well. For example, my third child had two nuchal arms (ouch!). I had Symphysis Pubis Disfunction with my 2nd and 3rd child, and very loose ligaments. This led to a very fast birth for my 1st (6 hours total), an actual precipitous birth for my 2nd (2 hours total), and the malpresentation for my 3rd. None of mine were c-sections, but I can see in differing circumstances my 3rd definitely could have been. I really feel this probably accounts for the association, and the c-section is certainly not causal, unless there is something also going on with the microbiome – but of course our understanding on that is so limited at this point.

    I also wanted to mention that this is the second time I’ve heard you talk about c-sections. And first I want to say I’m sorry you have felt so judged in the past by other mothers about your experience giving birth to your child. That really comes through strongly though, and your bias really shows in this area. I understand that it is very hard to separate emotion from science sometimes. In this episode though, you seem to indicate that c-sections can be life saving for a typical vaginal delivery – and you did not specify that there should be factors present indicating a need for that c-section before it becomes life saving. All research that I am aware of shows that vaginal delivery for a low-risk birth is safer than a c-section for mother and infant. C-sections become the safer option when there are other risk factors that may make vaginal birth the more risky option (breech or other malpresentation, multiples, alarming heart rate, etc.). I assume you didn’t mean to indicate this, and perhaps I misheard or misunderstood what you said. But I feel like it’s important to not give false information, and it is certainly false to indicate that c-sections are safer than a typical, low-risk vaginal birth. That is not to say that I don’t support a woman’s choice to have an elective c-section even if she has no risk factors. I most certainly do – it is her right to take on any added risks, just as it is the right of any birthing woman to take on added risks by using medications for pain, or choosing to give birth at a birthing center or at home, or whether to breastfeed or formula feed. My nonjudgmental support of women’s choices does not inform my interpretation of the research though. And to my knowledge the research is pretty clear on this one.

    Thanks.

  2. Has anyone seen the study about c-sections and birth canal pressure? In this study I believer there were 80,000 births in the study. It showed a 30% risk of autism in those who were born via c-section.
    I have EDS and have done a lot of reading- and I mean a lot. I have also wondered if I have high functioning autism/apsergers. If a mother has EDS, is the birth canal pressure lower? And in c-section, the baby is never exposed to the birth canal pressure at all. There is also a video on Youtube describing a condition in foals in which the horses present a kind of stupor at birth and it has been described like childhood autism. In the video, they talked about squeezing the foals with a rope in the abdomen until the fell asleep, upon which they released the pressure, the foals woke up, and were alert for the first time, as if they had just been born. They said it had to do with hormones and being “awake.” The birth canal pressure in older mares who have had mahy foals is of course, lower, and thus, the question came into my mind of people and c-sections. And that’s when I found the study online. What do you guys think?
    (Sory this is a poorly written comment, I am very tired)

    • There is no evidence linking EDS, birth canal pressure and an autism diagnosis. You should talk to your obstetrician about any precautions you should take as a person with EDS.

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