Coffee? Now a Pregnancy No-No, but Other Hazards Look Overblown

Caffeine and miscarriage, once questionably linked, now seem solidly connected.

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A few months ago, we published two lists of supposed hazards—including coffee, cats, and X-rays—that pregnant women are often advised to avoid. Some of these things really are best avoided. But others, experts told us, were overhyped threats. Note the past tense: were.

Medical science has since marched on, and one source of concern that then seemed overrated now appears to be a justifiable danger: A recent study found that consuming caffeine increases the miscarriage rate.

Prior studies also had linked high caffeine consumption among pregnant women to an elevated risk of miscarriage. But those studies didn't prove that drinking coffee or other caffeinated beverages can actually lead to a miscarriage; they showed only a statistical link. (Such statistical correlations are everywhere, and they can be misleading. Most people who live in nursing homes are old, for instance, but that doesn't mean you'd age more quickly if you moved to a nursing home.) The new study, in part by tracking women from early in pregnancy through delivery or miscarriage, makes a more convincing case for a cause-and-effect relationship.

Of course, pregnant women aren't the only people who need to worry about consuming too much caffeine. As my colleague Nancy Shute noted in a U.S. News cover story last year, Americans young and old are craving high-octane elixirs—and making doctors nervous. She followed up on that story by covering the controversy over caffeinated alcoholic beverages. Talk about something that pregnant women should avoid!