Wednesday, July 29, 2015

Correlation, Causation, & Skepticism

I recently read this article about mother’s weight gain during pregnancy and connection with childhood obesity, and I just can’t keep my Medical Anthropologist mouth shut.

Title: When mom gains too much weight during pregnancy, her child is more likely to be obese

Researchers in Greece: “conducted telephone interviews using a standardized questionnaire collecting information on the mother's age at pregnancy, amount of weight gained during pregnancy, pregnancy exercise level, smoking status, alcohol consumption and the body mass index of the child at the age of eight.”

And they came to the conclusion: “that the amount of weight gained throughout pregnancy, the   level of physical activity and smoking status was strongly associated with obesity in children. Moderate exercise during pregnancy was found to lower the risk of a child becoming overweight or obese in childhood, even after adjusting for the other maternal and child characteristics.”

So what’s the big deal?
First I want to say that while there MIGHT be a correlation between pregnancy weight gain and childhood obesity, that certainly does not mean there is a causal relationship between the two.  Said another way: Gaining too much weight in pregnancy might NOT cause childhood obesity.

In my professional opinion, there are so many other factors that could contribute to childhood obesity that were not looked at in this study.  Things like lifestyle, diet, current activity levels, genetics, and so many more that were not considered.  Perhaps moms who gain excess weight in pregnancy are more likely to be overweight in the first place and to continue that same lifestyle after pregnancy thus passing it on to their offspring.  Additionally, this was a retrospective study that asked mothers to recall very specific information about their pregnancy 8 years after the fact.  I have a 7 year old, and I honestly have a really hard time remembering specifics about my pregnancy with her. 

This is the problem with inflammatory headlines like this.  While they might get a lot of attention, the specious connections they are touting are not always accurate or whole pictures of what is actually happening and the risks involved. 

The point: Don’t freak out over every new claim that blames pregnant mothers for the outcomes of their children.  It isn’t always the mother’s behavior when their child was in utero that has long term effects. While that certainly is part of the picture, the whole picture is much more complicated than a simple headline can explain.

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