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Starting the day with a hot cup of caffeinated coffee or tea may sound divine to some, but it could have negative impacts for the children of people who are pregnant, according to a new study.
Children who were exposed to small amounts of caffeine before birth were found on average to be shorter than the children of people who did not consume caffeine while pregnant, according to the study published Monday in JAMA Network Open.
Children of parents who consumed caffeine while they were in the womb were shown to be shorter in stature at age 4 than those whose parents did not — and the gap widened each year through age 8, according to lead author Dr. Jessica Gleason, a perinatal epidemiologist.
“To be clear, these are not huge differences in height, but there are these small differences in height among the children of people who consumed caffeine during pregnancy,” said Gleason, who is a research fellow at Eunice Kennedy Shriver National Institute of Child Health and Human Development.
The American College of Obstetricians and Gynecologists currently recommends limiting caffeine consumption to less than 200 milligrams per day while pregnant.
For context, a mug of caffeinated tea typically has about 75 milligrams of caffeine, a mug of instant coffee has about 100 milligrams and a mug of filtered coffee has about 140 milligrams, according to the Cleveland Clinic. And even chocolate has about 31 milligrams of caffeine.
But the differences found in the most recent study were found even in the children of parents who drank less than half a cup of coffee per day while pregnant — well below the current guidelines, Gleason said.
It’s not clear whether this study effectively shows causation between maternal caffeine consumption and child height, according to Dr. Gavin Pereira, a professor of epidemiology and biostatistics at Curtin University in Australia. Pereira was not involved in the study.
“The correlation observed in this study can be explained by the existence of a common cause of both caffeine consumption and growth restriction e.g., poverty, stress, and dietary factors,” said Pereira in a statement to the Science Media Centre.
Why the concern over smaller stature?
If shorter height in early childhood were to persist into adulthood, there would be a chance those children could face the risk of poor cardiometabolic outcomes, such as heart disease and diabetes, which are associated with smaller stature.
But there is still no way to know if the difference would persist into adulthood, and studies like this that focus on population outcomes are no reason for individual families to panic, Gleason said.
These population-level trends should instead be taken together with other research for organizations to reassess their recommendations, Gleason said.
In the past, there were inconsistent studies regarding whether consuming caffeine during pregnancy impacted the fetus, but the evidence has come together in recent years, Gleason said.
A 2015 meta-analysis that reviewed all of the existing research found there is a dose response association between consumption of caffeine and smaller birth size. And a 2020 study revealed there is no safe level of caffeine for a developing fetus.
How to cut back
Even without the panic that Gleason cautioned against, some people might want to cut back on caffeine — and then find that it’s easier said than done.
Remember, caffeine is found in coffee, tea, soft drinks, energy drinks and shots, as well as cocoa and chocolate. It’s also present in fortified snack foods, some energy bars and even some pain medications. (For a more extensive list of caffeine content from various sources, check the chart from the Center for Science in the Public Interest.)
A 2016 Johns Hopkins University study found that it was helpful when individuals identified situations or moods in which they are most likely to crave caffeine so they could avoid situations that trigger cravings, especially during the first few weeks of modifying caffeine use. Caffeine drinkers could also have a plan for when cravings occur, like taking a five-minute relaxation break involving deep-breathing exercises.
Remember to always discuss any major lifestyle or dietary changes with your health care provider first, as changes may affect your mood or medical conditions.