Monday, April 9th, 2012
You may have seen or heard this morning about a new study that found links between maternal obesity and risk for autism. Here’s a breakdown on the study, the findings, and the take-home message.
What Did This Study Do? The research – published in Pediatrics – explored links between maternal metabolic conditions – specifically diabetes, hypertension, and obesity – and neurodevelopmental disorders in early childhood – particularly autism spectrum disorders (ASD) and developmental delays (DD). The sample was informative – it is a population-based sample in California that is participating in a very large investigation. That said, it’s important to keep in mind that maternal history of diabetes and hypertension during pregnancy, and obesity prior to pregnancy, were gathered retrospectively via a phone interview with the mother when kids were between 24 and 60 months of age, and also from medical records when available (which they were for over half the sample). I highlight this to emphasize that this is far from a definitive study - not that it’s a bad study, just that it is more like the first word, rather than the last word, on this topic. Do note that the available data suggested that moms could reliably report retrospectively (when they compared their responses to available medical records) – but still, this is not as informative as a prospective study. Moms were selected based on the profiles of 3 types of youth – those with ASD, those with DD, and a general population (GP) control group with neither condition. The researchers then set out to examine if there were links between the maternal metabolic conditions and these three groups of kids. So keep in mind here that this is a statistical test of association, not a more controlled experimental test that can, if you will, “prove” the associations. These kinds of studies are critical first steps to determine if future research is warranted – and not the last steps that convince the scientific community that there is a causative process at play.
What Did They Find? Keeping all of the above in mind (you have to in order to make sense of the results), the study did find a statistical link between a mother’s report of having any of the metabolic conditions and the odds of having a child diagnosed with ASD and DD. It was a moderate statistical finding (meaning statistically significant but clearly not the only factor that contributes risk for ASD and DD). To give you a sense of the data, here are the percentages of mothers with a metabolic condition, broken down by youth diagnosis:
ASD: 28.6% of the mothers
DD: 34.9% of the mothers
GP: 19.4% of the mothers
So you can see how this is a moderate statistical link – for example: 1) the majority of moms of kids with ASD did not have any metabolic conditions, 2) almost 20% of the moms of kids from the general population control group did have a metabolic condition; and 3) the finding comes from the somewhat elevated rates in the ASD and DD groups compared to the GP group. More fine-grained analyses showed that obesity in particular was associated with ASD (after controlling for other factors) – but that diabetes had an effect on a number of cognitive and social outcomes.
What’s The Take-Home Message? There are two messages from my point of view. First, from the perspective of science, the study authors devote most of their attention in their discussion of the results on the biological mechanisms by which maternal diabetes – not maternal obesity – may impact brain development in babies. This is an important avenue for future research and a key contribution from the study. Second, from the perspective of being a prospective parent, the real take-home is that management of maternal metabolic conditions is not only critically important for a number of health outcomes, but also for promoting brain development in the early years of life. Rather than focusing on metabolic conditions as “causes” of disorders, it’s probably better advised to consider them as modifiable influences on development. Maternal obesity is important in this sense because it is one of many factors associated with diabetes – though keep in mind that gestational diabetes can of course occur without obesity. Diabetes – whether in place prior to pregnancy or occurring during pregnancy – is important because it might have biological influences on brain development. So this study just reinforces the bigger message that I hope everyone is aware of – that pregnant women should get vigilant care for potential or existing metabolic conditions during pregnancy, especially diabetes. It’s critical for the well-being of both mom and baby.Add a Comment