Now that I'm pregnant, do I have to stop drinking coffee and avoid other sources of caffeine?

There's general agreement that pregnant women and those trying to conceive should avoid consuming large quantities of caffeine. But after decades of controversy and conflicting evidence, there's still no real consensus on how much caffeine is safe during pregnancy.

The March of Dimes advises women to limit their caffeine intake to less than 200 mg per day (that's about one 12-ounce cup of coffee). This recommendation was prompted by the results of a study published in the March 2008 issue of the American Journal of Obstetrics and Gynecology that showed that moms-to-be who consumed 200 mg or more of caffeine a day had double the risk of miscarriage compared with those who had no caffeine.

Not all studies show a link between caffeine consumption and a higher risk of miscarriage. Still, it may be smart to err on the side of caution and stick to the March of Dimes recommendation. (See the chart below to get a sense of the caffeine content of various types of coffee, tea, and other common sources.)

Of course, if you decide to cut out caffeine altogether, you won't get any arguments from your doctor or midwife.


Are there other risks besides miscarriage?

Yes. Because caffeine causes blood vessels to constrict, it may reduce blood flow to the placenta. And because it easily crosses the placenta and reaches your baby (who then metabolizes it very slowly), caffeine may directly affect your baby's developing cells.

A study in Denmark found that the risk of stillbirth more than doubled in women who drank a great deal of coffee per day – eight cups or more – compared with women who didn't drink coffee. Some studies suggest that high caffeine consumption may slightly reduce a baby's birth weight, but other research has shown no association.

One study found a link between maternal caffeine consumption equal to three cups of coffee per day and an increased risk of having a son born with undescended testes. This happens when the testes don't move from the pelvis into the scrotum as they usually do in late pregnancy.

Other research has shown that newborns whose mothers consumed more than 500 mg of caffeine a day had faster heart rates and breathing rates and spent more time awake in the first few days after birth.

One thing's sure: You'll feel better if you don't consume a lot of caffeine. It's a stimulant, so it raises your heart rate and may raise your blood pressure slightly, too. Plus, it can make you feel jittery and cause insomnia. Caffeine can also contribute to heartburn by stimulating the secretion of stomach acid.

These effects may be more pronounced or last longer than usual as you approach your due date, because your body breaks down caffeine more slowly as your pregnancy progresses. And that means a higher level of caffeine in your bloodstream – and in your baby's.

There's one more reason to cut back on coffee and tea during your pregnancy, whether it's caffeinated or not. These beverages contain compounds called phenols that make it harder for your body to absorb iron. This is particularly important because many pregnant women are already low on iron. If you drink coffee or tea, have it between meals so it'll have less of an effect on your iron absorption.