Having a baby is a big undertaking, and as such, comes with a whole set of responsibilities and sacrifices. That in itself might not come as a surprise – but what you might not realize is that a lot of it actually starts long before your tiny half-clone ever sees the light of day. From the moment you see that extra line on your pregnancy test, your life is based on an ever-changing list of things you can’t do, things you shouldn’t do, and things you’ve never done before but now you’re told you absolutely shouldn’t. forget to do on a daily basis.
Now, some of these bans are easier than others – after all, there can’t be that many people out there living off an all-shark diet. But others can be more annoying. Studies have suggested for years that caffeine — which about four-fifths of Americans rely on to wake them up and alert each morning — is not safe in any amount during pregnancy, as its consumption is associated with higher rates of miscarriage, stillbirth, low birth weight and childhood acute leukemia.
Compared to these results, being a little short might not seem so bad – but this is the result that most recently made headlines. In a paper published just yesterday, researchers found that children exposed to caffeine and caffeine metabolites in the womb were up to 2 centimeters (0.8 inches) shorter at ages four and eight than their peers without record.
And we’re not talking about day-and-night espresso-based parents here: the association was evident “even with maternal consumption below current recommendations of 200 mg per day,” the authors write. That’s the equivalent of about a cup of coffee throughout the day – an amount that, under normal circumstances, would barely register, but which the researchers found was comparable to a smoking habit in terms of reduced height in childhood.
So, is it time to ban caffeine during pregnancy, thereby avoiding a dire future in which everyone is just under an inch shorter than they would be otherwise? Well, let’s not be too hasty:
“This type of study is somewhat controversial as it can only prove an association, not causation,” pointed out Alex Polyakov, Associate Clinical Professor in the School of Medicine, Dentistry and Health Sciences at the University of Melbourne and Consultant Obstetrician, Gynecologist and Fertility Specialist at Melbourne IVF and the Royal Women’s Hospital, Melbourne, in a statement to the Australian Science Media Centre.
It’s an inevitable problem with studies like these, but randomized trials, which may have some chance of proving a causal effect, are simply not ethical when it comes to exposing babies to potentially dangerous substances. The best researchers can do is a retrospective study, where they compare results from pre-existing data sets and try to find a connection between them.
“The underlying assumption is that women who consume less coffee are identical in all respects to women who consume more, and the authors go to great lengths to ensure that this is the case using fairly sophisticated statistical techniques,” said Polyakov, who was not involved in the study, he added. “Unfortunately, this ‘unique difference’ can never be fully achieved.”
This is why this particular study is receiving something of a pushback from some academics. “[The] “The conclusion that ‘increasing levels’ of caffeine and paraxanthine, even in low amounts, were associated with shorter stature in early childhood is flawed,” commented Gavin Pereira, Professor of Epidemiology and Biostatistics at Curtin University.
“This finding indirectly implies that as caffeine consumption increases, so does the risk of shorter stature,” he explained. “Rather, all that can be concluded from this study is that children born to women who consumed higher levels of caffeine were closer than children born to women who consumed relatively lower levels of caffeine.”
And there are many possible reasons why this might be the case. Maybe the researchers are right and it is in fact that exposure to caffeine in the womb stunts growth later in childhood – but then again, it could be that working longer hours during pregnancy leads a person to drink more caffeine and to experience more stress. Perhaps it is the stress levels during pregnancy, not the caffeine, that is responsible for the shorter height in their children.
Alternatively, higher caffeine intake may be a symptom of poor diet. In this case, perhaps malnutrition plays a role in the height of the offspring after birth. Hell, maybe it’s just that shorter people need more caffeine a day to make up for all the extra energy we expend reaching up for things that are placed slightly out of reach—the thing is, the study didn’t, and indeed couldn’t, get consider any of these possibilities. We just don’t know.
But that doesn’t mean the study should be ignored entirely. “We already know from previous research that there is a link between high caffeine consumption (>300 mg per day) and lower birth weight and preterm birth, and intake above 350 mg per day is associated with pregnancy loss (miscarriage and stillbirth)” , commented. Helena Gibson-Moore, nutrition scientist at the British Foundation for Nutrition, in a statement for the UK Center for Science Media.
And while the study falls short of proving a causal link, Gibson-Moore pointed out that “the association between maternal caffeine consumption and reduced child height is biologically plausible given that caffeine and paraxanthine cross the placenta.”
Essentially, this study probably shouldn’t cause you to panic if you’re pregnant or recently pregnant and partial to a cup of joe now and then — but it’s a useful reminder that caffeine, the world’s most widely used psychoactive substance, is something which does not carry zero risk to the developing fetus.
That said, there are very few things out there that do. Even paracetamol, sometimes known as acetaminophen, was recently downgraded from “one of the only painkillers available to pregnant women” to “may be linked to neurological disorders, language delays, reduced IQ and more”.
Overall, advises Polyakov, “a healthy balanced diet is the best possible strategy.” A small amount of coffee during pregnancy, he said, “is probably unlikely to cause significant harm to either a pregnant person or the offspring, despite the findings of this study” — and indeed, reading too much into the results of studies like this one can actually to do more harm than good.
“Advice to unnecessarily restrict pregnant diets can actually be counterproductive and create anxiety and guilt if women can’t stick to it,” Polyakov said. “The bottom line is that if one’s well-being is enhanced by a cup of coffee, there’s probably no harm in drinking it.”
The paper was published in JAMA Network Open.
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