Is It True That Caffeine Causes Miscarriage?

What the Research Says About the Safety of Caffeine During Pregnancy

Young woman reading a newspaper with a gigantic cup of coffee. Credit: Photo-Biotic / Getty Images

If you read the news, chances are you've seen headlines now and then proclaiming the dangers (or lack thereof) of caffeine during pregnancy. Depending on the week, you might read anything from "caffeine is harmless in moderation" to "avoid caffeine at all costs and everything that contains it." It's understandable if people are confused.

Conflicting Research About Caffeine and Pregnancy

In recent years, a number of research studies have looked at the link between coffee intake and miscarriage.

A few studies have found that high intake of coffee was statistically correlated with pregnancy loss, but other studies have found no link.

Some researchers doubt the coffee/miscarriage link; instead, they blame morning sickness for the association. Other studies have found that having morning sickness is correlated with a lower risk of miscarriage (probably because pregnancies destined to miscarry produce lower hormone levels and fewer body changes). These researchers theorize that women who are destined to miscarry are more likely to drink coffee during pregnancy (because it doesn't make them nauseous), whereas women who will not miscarry are more likely to have morning sickness and be repulsed by coffee.

Of course, the link between coffee and miscarriage may not be so simple as being due to morning sickness. One 2003 study examined coffee intake alongside nausea and found the two factors to be independent of one another.

And it is too early to say whether or not the finding will lead to anything, but one 2006 study by Swedish researchers found a genetic variant that might be associated with miscarriage risk from coffee intake -- which the researchers theorized might account for differences in study findings.

To Drink Caffeine or Not to Drink Caffeine During Pregnancy?

In summary, the verdict is still out on whether high caffeine intake during pregnancy can cause pregnancy loss.

With the available evidence in mind, a reasonable conclusion would be that it's a good idea to restrict your caffeine intake during pregnancy as a safety precaution -- there's enough evidence to say that moderate to high caffeine intake might be linked to miscarriage.

On the other hand, if you've already had a miscarriage, you should not look back and assume that it happened because you drank too much coffee or ate too much chocolate while you were pregnant. There's just not enough evidence to draw such conclusions, and it's probably more likely that caffeine had nothing to do with your miscarriage.

The March of Dimes and other health agencies recommend 200-300 mg a day of caffeine as a reasonable guideline for safe intake of caffeine in pregnancy. (For reference, one 8-ounce mug of brewed coffee has between 60 and 120 mg of caffeine.) 

So, to be on the safe side, you could switch to decaffeinated coffee, but it's probably fine to go ahead and have that morning cup of coffee if you want it -- just don't drink the entire pot!


Other Common Questions About Caffeine and Pregnancy Loss

Why would caffeine be linked to miscarriages if most miscarriages are caused by chromosomal abnormalities?
It's true that the majority of early miscarriages result from chromosome issues in the baby, and it follows that if caffeine consumption does cause miscarriages, it probably is a factor only in a small percentage of miscarriages. But pregnancy can affect women's ability to metabolize caffeine, and it does appear that caffeine and metabolites of caffeine can cross the placenta, so it is possible that prolonged exposure to caffeine might harm the baby. Researchers are studying various mechanisms for how and why this might occur.

If caffeine causes miscarriages, how come so many women can guzzle coffee all throughout pregnancy with no signs of problems?
There's considerable genetic variation among individuals in the ability to metabolize caffeine. It's possible that some people will never have any problems with caffeine in pregnancy while others might have numerous problems. Again, researchers are still studying the matter.

Is it possible that chemicals in the coffee itself are responsible for this link, or is caffeine really the culprit? Is decaf coffee safe?
Researchers have considered this question, as coffee has often been highly processed by the time it ends up in your mug, but the research linking caffeine to pregnancy loss has found a similar link regardless of the source of caffeine. Decaffeinated coffee is probably safe as a way to satisfy coffee cravings if you are having them and has never been tied to any pregnancy issues.


Norman, Robert J. and Vicki Nisenblat. "The effects of caffeine on fertility and pregnancy outcomes." UpToDate.

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