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Here’s the title of a press release that appeared this week from the University of Colorado: “Vaping nicotine during pregnancy may be no safer for developing fetus than smoking cigarettes”.
That’s a scary-sounding claim: a lot of people vape, and a lot of them do so to try to give up smoking while they’re pregnant. Could it be that this is pointless, and vaping is just as bad for their unborn child?
The press release goes on to state how “vaping nicotine during pregnancy can be detrimental to the baby”, and talks about “the popularity of vaping among young people”.
I put it to you that this press release sounds an awful lot like the study was about humans: it mentions “young people”, it mentions “the baby”, and has more along those lines.
But – and if you’re familiar with hyped press releases you might have guessed what I’m about to say here – the study was in mice.
The press release does mention that the researchers used an “animal model” – but because the context seems so strongly focused on humans, you could be forgiven for thinking the animal model (a jargon term in itself) was something in addition to an experiment with people.
But no humans were involved in the study. Instead, the scientists put three pregnant mice in an “exposure chamber”, puffing vape gas in every 20 seconds or so for four hours every day. They were compared to six pregnant mice who weren’t “vaped” in this way. That’s the “animal model” – it’s supposed to be a simplified, easier-to-control model version of what humans do.
You can already see the absolutely tiny sample size involved here: nine pregnant mice overall, meaning that any results are going to come with enormous uncertainty.
What were the results? First, the vaped mice had smaller litters of babies than the control ones – though the statistical test was right on the borderline of being statistically significant, meaning it wasn’t particularly convincing. Second, there were no statistically significant differences in the birth weights of pups between the vaped and non-vaped mice.
That’s unexpected, because the press release led us to believe that vaping was no different from smoking – and we know from large, good-quality studies (in humans) that that smoking during pregnancy is linked to lower birth weight. The authors write: “Perhaps higher doses of nicotine would significantly affect fetal birth weight” – that might be true, but it’s just a speculation, given the results of this study.
Tiny sample size really hampers any true comparison
The researchers go on to look at differences in the face shape of the mice, comparing different measurements that might or might not relate to measurements in human babies (and again, we know that some facial measurements differences are linked to smoking in pregnancy). They also looked at some differences in the expression of genes between the vaped and control mice. But as before, the tiny sample size really hampers any true comparison, and the overall issue—that the pups of the vaped mothers didn’t have lower birth weight—hangs over the whole study.
And here’s the thing: in large human studies where cigarette use was compared to vaping during pregnancy, the researchers found the results you might expect: using tobacco is related to more adverse outcomes, whereas there was nothing too obvious to report for e-cigarette users.
In other words, smoking cigarettes is worse (remember that cigarettes don’t just contain nicotine, but a whole host of other dangerous chemicals that we’re really certain cause all kinds of damaging effects). It’s something we’d ideally want to reduce in pregnant women, and if e-cigarettes can help them give up smoking the “real thing”, they’re in many ways a good thing. Indeed, a study published last year – a randomised trial, so good-quality evidence – found that pregnant mothers who used vapes were more likely to give up smoking than those who used nicotine patches – and that if anything, low birthweight was rarer in the vaping group than in those who used the patches.
Nobody’s saying we should encourage e-cigarette use in pregnant women – ideally you’d give up nicotine entirely. But you’ve got to ask what the alternative is. If mothers would otherwise be smoking tobacco, that’s a far more dangerous world for their babies.
Given all this context, is it responsible for scientists to put out a press release, on the basis of a tiny study of an entirely different species, that draws an equivalence between smoking and vaping, fueling fears in mothers who might be doing their very best to give up what, after all, is an extremely addictive drug?
I’ll leave that as an exercise for the reader.
Other things I’ve written recently
Australia (which, incidentally, has a very strict ban on vaping that’s unusual compared to all its comparator countries) has now legalised psychedelics for use in psychiatric therapy. I actually lean towards legalising these substances – if only to do more research on them. But given the low quality of the evidence that these drugs can improve people’s mental health, as I wrote about here, I’d be reluctant to give them out to patients just yet.
The respected TV presenter Fiona Phillips this week announced that she has early-onset Alzheimer’s disease. I wrote a little explainer of what we know about the genetics of Alzheimer’s, and why some people are at much higher risk than others.
Science link of the week
I’ve recently discovered this brilliant science website called Dynomight. It has tons of highly-informative, insightful essays on all sorts of topics which will appeal to anyone who’s a reader of this newsletter. I actually linked to the Dynomight aspartame article in my piece on the same topic last week: it’s now been updated to take into account the more recent controversy. Do take a look around the site.
This is Science Fictions with Stuart Ritchie, a subscriber-only newsletter from i. If you’d like to get this direct to your inbox, every single week, you can sign up here.
