Flu, Pregnancy, Autism: What To Make Of Exploratory Studies

On the one hand, the recently published paper suggesting a link between flu in pregnancy and risk for autism is an important one. Researchers continue to look for clues for any of the multitude of risk factors that might contribute as partial causes of autism. There is certainly interest in the prenatal period and exposure to many potential influences. 

On the other hand, as a scientist and parent, I start to cringe when I see studies like this one getting translated into hyperbolic headlines. Why? Simply put, what we’ve really learned from this study is that we might want to try to further study the associations between flu, pregnancy, and autism. That’s it.

Now, that might seem like a puny contribution. It isn’t. But what you need to know is that all studies reported in scientific journals do not have the same goal. Some hone in precisely on a given topic and try to cement knowledge with rigorous hypotheses. Others, however, provide an initial clue that something should be looked at closer. That’s where we are at with the flu, pregnancy, and autism link.

You should think of this study as exploratory. Why? There are a number of reasons, and I’ll list just a few. First – the study relied entirely on mother’s recollections. This isn’t the optimal way of studying the association – not because moms (or anyone else) are unreliable, it’s just that the most precise way would be to use a number of methods (including prospective in-person assessment and reporting, medical records, etc) to record data that are not easy to catalogue. Second, the study looked at a whole bunch of potential factors in a very large sample. This means that the findings that come out as significant can be due to chance. While this is always the case in science, it’s especially so when there is a really big sample (simply because a large sample means very small results can reach statistical significance) and lots of potential associations are tested – and it’s the reason that science demands replication across a number of studies before we agree that a finding is established. Third, this point is reinforced by the finding itself – the risk increased from 1% to 2%. Any explanation in science is important, but when you look at the numbers this way it’s a bit more realistic (and sobering) than headlines that scream that the risk is doubled. Yes it was – from 1% to 2%. Think about the “margin of error” you heard about all through the recent presidential election with respect to polling – the same principle applies here. This difference could be a systematic result – or just chance. And right now the effect is rather modest. The bottom line is that more studies are needed to build on this to figure out exactly what is going on.

I’m a big fan of parents – and anyone who is interested – getting closer to science, especially new studies as they come out. But if we are going to support that, we need to explain more about the studies and what we think they mean, and don’t mean, right now. So here you go. Right now, it’s certainly the case that physicians and public health experts continue to suggest that pregnant women get vaccinated for the flu. If you are pregnant, talk to your doctor about that right now. Right now, extrapolating from these findings and trying to figure out if a child is diagnosed with autism because the mom got the flu when she was pregnant is not a productive exercise. Pointing a finger at a pregnant woman who is sick and saying that her unborn child will be diagnosed with autism is certainly not productive and would be misguided (not to mention hurtful). These exploratory studies are done to help guide future practices, not assign blame or create panic. They only provide a guide to future scientific projects that might shed more light and someday deliver more helpful guidelines for preventing autism.

Question marks via Shutterstock.com (because that’s the take-home message right now)

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