Drinking coffee while pregnant could make your kids shorter by a few centimeters, a new study says

Pregnant women who consume large quantities of caffeine tend to have children who are shorter, when compared to the children of women who consume low quantities of caffeine or none at all, according to a study from researchers at the Eunice Kennedy Shriver National Institute of Child Health and Human Development in Bethesda, Md., in addition to Johns Hopkins Bloomberg School of Public Health. The study was published Monday by the Journal of the American Medical Association.

The study followed thousands of children, ages 4 to 8, of a diverse group of women with varying levels of caffeine consumption during pregnancy. In one group studied, children of women with the highest level of caffeine consumption while pregnant—equivalent to around six cups of coffee or more a day—were, on average, 1.5 centimeters shorter at age 7 than children of women with the lowest level of caffeine consumption while pregnant—equivalent to a quarter cup of coffee a day or less.

In another group studied, children of women with the highest level of caffeine consumption while pregnant were between .68 and 2.2 centimeters shorter than children of women with the lowest level of caffeine consumption. The gap in height widened between ages 4 and 8, researchers stated.

The findings indicate that “maternal caffeine consumption is associated with long-term decreases in child height,” the authors wrote, though they’re unsure as to why that might be.

Appearance aside, why might height matter? Shorter stature has been associated with an increased risk of heart disease, diabetes, and obesity as an adult, potentially putting the children of high-caffeine consumers at greater risk for health problems later in life, according to the study. 

Other studies like one published in 2018 that looked at the caffeine intake of nearly 51,000 pregnant Norwegian women found an association between high maternal caffeine intake and an increase in a child’s BMI, or body mass index. But the new study did not come to a similar conclusion. Further study is warranted, the authors wrote.