STATS ARTICLES 2007

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Coffee and Pregnancy: How Much Can You Drink?

Just what does three cups mean?

Kudos go to MSNBC which reported that “Up to 3 cups of coffee OK for pregnant moms.The willingness of news organizations to report on a ‘negative’ finding (a result where there is no proven effect of some substance) is news in and of itself. The MSNBC article is based on a recent research experiment that finds moderate caffeine intake by pregnant women to have no adverse consequences for their babies, at least not in the second half of the pregnancy.

The study was published in the January 27 edition of British Medical Journal. Like most convincing scientific and health-related studies, it follows on the heels of a lot of research, and is confirmed by years of other experiments suggesting similar results. A quick visit to pubmed, the National Institutes of Health’s searchable database of scientific articles, shows how extensively caffeine and its impact on pregnant women and their newborns has been scrutinized.

That said, what do “three cups of coffee” mean? Three big cups? Strong or weak? Unfortunately for the public, MSNBC didn’t bother to say.

Of course, researchers don’t measure caffeine in units of “cups of coffee”. Instead they use milligrams (mg) of caffeine – and the beverage could be coffee or any other caffeine-containing drink. After all, a cup of instant coffee (used for this study) is not a cup of coffee at Starbucks.

The BBC reported on the same story, with a more detailed analysis. In particular, readers are told that the study compared two groups of women whose caffeine intake differed by, on average, 182 mg of caffeine per day. The BBC added that the UK advises pregnant women to consume no more than 300 mg of caffeine, adding that “this equates to the amount of caffeine in three cups of instant coffee, six cups of tea, eight cans of cola or eight bars of chocolate.” (For coffee purists, that's roughly five espressos from arabica beans.)

The American version stuck with “three cups of coffee” and vague words such as “moderation” to describe the result. MSNBC didn’t make any mention of milligrams of caffeine, or what common products women could measure their caffeine consumption by. As it turns out, not all cups of coffee are created equal.

One eight ounce cup of instant coffee comes in at about 60 mg of caffeine, while eight ounces of Starbucks brewed coffee is more than three times that amount, at over 180 mg of caffeine. And some studies of specialty coffee have found that Starbucks brews vary – getting as high as 280 mg for eight ounces. Compare that to brewed coffee from Dunkin’ Donuts, which comes in at under 80 mg for eight ounces.

Given the American love of large sizes, some pregnant women might believe “three cups” consist of three 16 ounce brews from Starbucks, rather than three eight ounce watery cups of instant coffee. That could amount to over 1500 milligrams per day, far over the amount considered to be “moderate” by research on coffee consumption and pregnancy.

So while MSNBC valiantly reported on a finding that might otherwise not make a splash because there were no birth defects to be splayed on the front page, they regretfully neglected to tell people the most important news: “three cups” of coffee translates into just a small cup of Starbucks’ daily brew.