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Will caffeine consumption during pregnancy make it more likely that your infant and child will be fat? A report from the Norwegian Mother and Child Study on caffeine intake and infant body weight made all the news. Let's take a little minute to review caffeine in pregnancy and this study before the caffeine drinkers get too worked up.

We've talked before on The Scope about the recommendation that women limit their caffeine intake to less than 200 milligrams per day. Now that would be about two small cups like the cups that your mother used to put coffee in, or one 12-ounce cup. Not the extra grande or supersized cups of coffee, or cans, or Coke cans of caffeinated soda. The reasons for this recommendation come from the Scandinavian studies that are very large and can follow moms, babies, and dads of babies.

Caffeine's Impact on Pregnancy

There's a suggestion that consuming more than 200 milligrams of caffeine per day slightly increases the risk of miscarriage, and consuming large amounts of caffeine or caffeinated beverages, that's usually coffee in Sweden and Norway, can restrict the growth of fetuses in development. This suggests that large amounts of caffeine may be a stressor in pregnancy. We have evidence that babies who are stressed in the uterus are more likely to have health problems as children and adults. One of those problems is being overweight.

Examining Caffeine Intake and Infant Body Weight

The study looked at 50,000 pregnancies and followed the kids' weights at their well-child check-ups. Compared to women who took no caffeine or very little caffeine in pregnancy, less than a cup of coffee a day, the kids were a little smaller at birth but then put on weight faster throughout childhood. The kids of women who consumed a lot of caffeine, four cups or more equivalent in tea or caffeinated sodas a day, were on average 2.5 ounces heavier at 3 to 12 months, 4 ounces heavier at toddlerhood, and 12 ounces heavier at 8 years of age.

Now, that isn't a lot, significantly less than one pound, but it shifts the curve of weight so that slightly more kids were overweight in the high-exposure to caffeine group. To say that another way, for any one child the differences would be small, but it would be significant for a population of children.

Now, this is a very complicated issue. This is not a randomized trial where 1,000 pregnant women get a boatload of coffee and 1,000 women don't get any caffeine. These outcomes from the caffeine and pregnancy study come from large observational studies where data were collected during the pregnancy and the kids' early growth and analyzed later. So women who drink a lot of coffee in pregnancy are different in other ways than women who don't drink caffeinated beverages.

In this study on caffeine intake in pregnancy from Norwegian moms, the higher the caffeine intake, the higher the likelihood of a mother being older than 30 years of age and having had more than one baby. Women who took a lot of caffeine ate more calories and were more likely to smoke during pregnancy. Moreover, women with very high caffeine intake were more likely to have low education, have been obese before pregnancy, and have partners who were obese and smokers compared with those consuming less caffeine per day.

All of these factors can be stressors in pregnancy and can change the baby's response to stress after birth. All of these factors may also play into a child becoming overweight. In this study, they had so many pregnancies that they could exclude women who smoked and whose babies were underweight at birth. And that's a risk for extra weight gain.

However, growing up in families where moms and dads may be overweight, smoke, and drink a lot of caffeinated beverages, may mean that there are other dietary differences.

Caffeine Recommendations during Pregnancy

So what's the takeaway from this study? Well, it's another reason to limit caffeine intake in pregnancy. You know your caffeine sources. Yep, chocolate, caffeinated teas, and coffee, and it would be best to avoid caffeinated sodas altogether because the sugar or the sugar substitute probably isn't so great for you or your baby. And the can is lined with stuff that's been associated with excess baby weight gain. That's baby weight of the baby, not the mom.

Limit to one 12-ounce cup of coffee or two 6-ounce cups of coffee a day or equivalent in tea or chocolate or less. The amount of caffeine in coffee, sodas, and teas may vary, but you can check it out on the internet. Be calm, be wise, be moderate, and thanks for joining us on The Scope.

_{updated: November 10, 2023
originally published: May 31, 2018}