This is a quick story about the findings from a small study of pregnant mice. The study showed that mice given the opportunity to exercise during pregnancy (by running on a wheel) had offspring that were more physically active than the offspring of pregnant mice who were not permitted to exercise.
This story was concerning on several fronts:
We suggest an alternate message for moms: Wait for larger, controlled human studies before buying into such a link. And we would urge on all of us a greater degree of skepticism for news releases that promote such generalizations on the basis of a small study.
Active human beings are generally healthier human beings. But the prospect that level of parental activity during pregnancy might influence the eventual activity levels of their children—and that such influence is biological, not environmental—is novel and would be of great interest if it proved to be true.
The intervention here is the act of running—in the case of these furry participants, running in an exercise wheel. If the assumption is that the human equivalent is also running (and not weight lifting as the story’s image indicates), the primary cost to people would be one of time.
The story explains that levels of physical activity in mouse kids of active mouse moms were 50% greater than were activity levels of kids of mouse moms who were prevented from using a wheel. Normally, we’d expect to see these numbers quantified in absolute terms, but since we’re talking about mice, we don’t think it’s essential to get too precise, as that might feed the perception that the results are applicable to humans.
Possible harms of vigorous activity during pregnancy were not discussed.
While the story makes clear, early on, that this study was conducted in mice, it fails to note that the design utilized only a handful of the little critters: 12 to 16, according to the peer-reviewed article in The FASEB Journal. The reporter clearly understood the potential gap between mouse and human studies and included a brief section heralded by the question “How does this relate to our own species?” But the subsequent text, instead of highlighting the challenges of generalizing from mice to moms, offers the reader encouragement to make that jump.
In some ways, this story is not about disease but about wellbeing.
The unfortunately thing here is that a small mouse study is now circulating the internet on a number of news sites, possibly impacting the decisions pregnant women make, when this research isn’t at all conclusive about what humans should or shouldn’t do during pregnancy.
There appear to be no overlooked conflicts of interest in this story. However, because there were no independent sources, this falls under Not Satisfactory.
Although the story refers repeatedly to “exercise,” the only physical activity studied here was mice running on an exercise wheel, and not other forms of vigorous activity. That’s the limitations of mouse research, and why these sorts of stories should be reported on sparingly.
Running as an activity is presumably accessible to women.
The article notes that the current study goes beyond available observational studies in humans by utilizing an experimental design in mice.
This brief story is highly reliant on a news release. The reporter has made no obvious attempt to contact the researchers for further information or to obtain reactions from other scientists.