Drinking Coffee During Pregnancy May Lead to Shorter Kids

Drinking coffee while pregnant may cause your child to be shorter later in life, according to a new study

I remember when I was growing up and my mom told me I couldn’t drink coffee as a kid because it would stunt my growth. It turns out, she may have been on to something: a new study found that drinking coffee (and other caffeinated beverages) while pregnant may be connected to having shorter kids.

The study, which was published in JAMA, followed a cohort of moms from 1959 to 1965, and their kids from 1960 to 1974. That data was compared to similar data gathered by following more recent cohorts of moms (from 2009 to 2013) and kids (from 2017 to 2019). The researchers measured the amount of caffeine and paraxanthine (the metabolite of caffeine) in the moms’ blood during the first trimester of pregnancy. Then, they tracked the kids’ growth up until age eight.

The data showed that moms who had more caffeine and paraxanthine in their blood during pregnancy consistently tended to have shorter children.

“The main takeaway is that even low exposure to caffeine during pregnancy was associated with shorter height in childhood,” said Jessica Gleason, Ph.D., MPH, the study’s author. “There have only been a handful of studies that are similar to ours, and none had really evaluated height separately from overall BMI. Considering prior research, I was a little surprised that we found no association between caffeine exposure during pregnancy and child weight but found such a consistent association between caffeine and child height even up until age 8.”

But before you decide to give up coffee altogether during pregnancy (a time when a caffeine boost may be more needed than ever), the difference was small—about two centimeters between kids whose moms drank the most caffeine and kids whose moms didn’t drink any at all. Gleason said more research is needed to understand the full implications of the study’s findings.

Related: Drinking Alcohol & Coffee Could Help You Live Longer, So Moms Should Be Immortal

“The clinical implications of this work are unclear because the height differences we observed are so small,” she said. “It would be important to determine whether height differences persist beyond childhood, as shorter height in adulthood has been associated with a higher risk of diabetes and cardiovascular disease.”

There’s been a ton of debate over how much (if any) caffeine is safe during pregnancy, and despite this study, experts still generally agree that up to 200 milligrams (or one 12-ounce cup of coffee) per day is just fine.