Tuesday, 12 November 2013

Exercise In Pregnancy Boosts Babies Brains. Well, Possibly

According to an article on the Guardian website on Sunday:

"Pregnant mothers who exercise boost babies' brains. 
Weekly exercise by mothers linked to better mental performance in later life".  

If you suspect I'm about to lay into this article, you'd be right. Somebody please sound the using dodgy science to attack women, again, klaxon.

The claim is based on a study led by Elise Labonte-LeMoyne at the University of Montreal. The first thing to note is that she was presenting her findings at a scientific meeting. You could in theory say almost anything at one of these meetings. The evidence presented does not have to first be subjecting to the scrutiny of peer review as happens with published scientific papers. I'd therefore always advise caution before taking anything unpublished too seriously.

But lets have a look at what the study actually did. They told ten pregnant women to exercise three times a week and six pregnant women not to exercise. Eight to 12 days after their babies were born, scientists tested for a specific form of activity in the sleeping infants brains. This apparently indicates how mature the brain was.

Ten women in the test group six in the control. These are TINY numbers. Far too small to give statistically meaningful results given the huge number of potential variables. As there is no published paper and I don't happen to have been at the meeting, I don't know  how or if these were controlled for. We don't know, for example, if all these babies were born at full term. With the numbers so low a single premature child in the control group could sway the results of the entire study. 

How sedentary were the control group?  I did little formal exercise in my second pregnancy but I was chasing after a very active three year old most days. I suspect that added up to far more than the hour a week of exercise for the test group in this study. Is it even ethical to insist that a group of pregnant women do no exercise? Quite apart from the practicalities of it, it seems to be common sense that a bit of exercise in pregnancy is a good idea.  Giving birth and then caring for a small baby is likely to be by far the most physically demanding thing that most women will ever do, it makes sense to do a bit of training if you can.

Does brain function at a few days old really equate to "mental performance" in later life? To me this seems like a pretty big leap. Ok so a kid has a slightly less mature brain at eight days old, it's surely not that unlikely that they could catch up a bit over the next 18 years?

I also wonder about the design of the study. Generally speaking randomised controlled trials like this one (the participants were randomly assigned to exercise or non exercise groups) are seen as the gold standard. However, for this to really work you would need a very large number of women who were all very similar (how healthy are they? How active before pregnancy? Were the babies breastfed? Did they have time in NICU? etc.etc.)  They also have to be willing to take part and I for one wouldn't sign up for something if it meant I had to be sedentary for months. 

It's not the study itself that I'm really annoyed with though. What I'm wondering is - Why on earth is this a story from a major national news outlet? Ok we might expect it from the Daily Mail, but the Guardian is usually a bit better about science reporting.

This is a scientist talking about a very small and preliminary study. It may be academically interesting to others in her field and it may form the basis of further, larger studies which would be worth reporting. But at the moment it tells the rest of us absolutely nothing. It really is a non story. Except that it is a story about women's bodies and what they choose to do with them and that, it seems, is always news.

SB

1 comment:

  1. I also had similar thoughts when reading this article - but I think I picked it up in the Metro so thought nothing of it. It is very annoying when you can't find the back up or other robust studies supporting theories. The brain of a youngster, as any mother will know, develops at different rates between individuals; and yet some how by the age of 5 they all seem to have very similar abilities (give or take the amount of input on behalf of the carer in the interim years), no matter where they start from (the caveat being medical/genetic anomalies of cause).


    anyway rant over

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