Kickstarting the day with a hot cup of coffee sounds like a winning idea for many, but it could have negative impacts on children during pregnancy, according to a recent study. The study published in JAMA Network Open found that the slightest caffeine exposure to children when pregnant resulted in shorter children, on average than children of mothers that did not consume coffee when pregnant.

“Though the clinical implications of an approximately 2-cm height difference are unclear, our findings for height are similar in magnitude to those of children whose mothers smoked during pregnancy,” corresponding author Dr. Katherine Grantz and the team write in the study. 

Prior studies have found a strong link between increased caffeine intake during pregnancy and a reduction in a child’s height. Researchers were then curious to investigate whether cutting down intake to less than two cups of coffee (200mg) — well below the clinically recommended guidelines – would still lead to shorter kids. Importantly, this is the first-ever study of its kind.


Dr. Katherine Grantz together with Dr. Jessica Gleason and the rest of the team set out to examine levels of caffeine and its end product ‘paraxanthine’ in blood samples gathered from over 2400 pregnant women in the US. The team looked at a previous pregnancy cohort on the link between mothers that consumed a high amount of caffeine and mothers with low caffeine consumption. In addition to the maternal caffeine intake, they also took into account the child’s Body Mass Index (BMI), weight, height, and obesity risk. 

During a follow-up period of over 8 years, the researchers regularly monitored the children from birth till they attained 8 years. This was done to collect measures of the children’s heights and weights over time.

Results of the Study

From the two pregnancy cohorts examining both low and high caffeine consumption, the team found that the level of concentrations of caffeine and its metabolite, paraxanthine in the mother, even at low levels, had a consistently lower height difference of 2 cm from ages 4 to 8.

On top of that, they found that the shorter stature persisted till at least age 8 after a longitudinal follow-up. This, therefore, led the researchers to conclude that just a cup of coffee during pregnancy has the long-term ability to knock inches off a child’s height.

As much as shorter heights might seem more or less irrelevant. However, the study authors note that smaller stature could pose serious harm to health should it persist into adulthood. For instance, there are chances of increased risks of multiple cardiometabolic diseases such as heart diseases. Likewise, the possible risks of obesity and diabetes.

Although, the major limitation of this new study is that the researchers failed to take into account the paternal height as well as the maternal diet.

Given the evidence found from eventual shorter height in 8-year-olds who were exposed to little amounts of caffeine before birth. Still, the team sees the need for more studies extending into puberty and adulthood to further evaluate growth implications. 

To sum up, this study lays large emphasis on the need for mothers-to-be to deter from taking caffeine when pregnant.

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