The journal Pediatrics released a study recently claiming an association between autism and maternal obesity during pregnancy. As soon as I heard this study being splashed all over the media, I winced. As much as the journalists point out “correlation, not causation”, they also throw out vague warnings about obesity. On NPR this morning, the story was covered as being another casualty of the “rather striking epidemic of obesity”, and, in this article in the Washington Post, despite the lack of causation, the author warns “[s]ince more than one-third of U.S. women of child-bearing age are obese, the results are potentially worrisome and add yet another incentive for maintaining a normal weight, said researcher Paula Krakowiak, a study co-author and scientist at the University of California, Davis.”
Because, it’s all just our fault because of our behavior, right moms?
I don’t think so.
I was already pondering autism and causation recently. It has been an interest of mine for quite some time. Before I knew that I was going to go to medical school, when I got my first job at the first health food store, I was intrigued by the parents of children on the autism spectrum who would come into the store, desperately seeking anything to help. Many were trying gluten-free, casein-free diets, long before the recent gluten-free craze. Many were buying supplements. I was surprised at how many children on the autism spectrum there were. This was in the mid 90’s, and my first glimpse at the burgeoning numbers of children living with this diagnosis. I decided I wanted to work in the field, and help unravel this mystery for these parents.
Since then, my focus has obviously shifted. However, I have two cousin Susans with two sons each on the autism spectrum or with related developmental delays, which were also included along with autism in the study. One is closely related to my younger son’s father, and one is closely related to me. They are not related to each other at all. I know it is just anecdote, but I was already trying to look for a pattern – something they had in common. Why were their children affected, and mine not? I was overweight, possibly obese according to BMI, during both pregnancies. One of my cousins was, and one wasn’t.
Well, this study made things click in my head. There is a confounder strongly associated with obesity that was not looked at in the study. It is also associated with high circulating androgen levels, which have a known association with autism spectrum disorders. And, interestingly enough, both of my cousin Susans have this condition, and I don’t. It’s polycystic ovarian syndrome (PCOS). It is a lot less common than obesity, and would probably make more sense as a causation, both prevalence-wise, and physiology wise. I did a quick literature search, and couldn’t find anything on it.
I am not sure how difficult it would be to do a case-control study on this. It would be easy if I was at Kaiser. It was probably easier to look at weight and height at delivery than delve into gynecologic histories to find if there was any diagnosis of PCOS in the subjects of the study.
Well, trying to do some research on this is a definite possibility. Hopefully in the near future.