Most women already know to eliminate smoking, alcohol and most medications during pregnancy, but what about caffeine? Certainly a single morning cup of eye-opening caffeine must be safe? Well think again. A new study
published in this month’s American Journal of Obstetrics and Gynecology, looked at 1,063 pregnant women in San Francisco over two years who were members of the health insurer Kaiser Permanente in the San Francisco area. Following a positive pregnancy test by a lab, they interviewed in person every woman who agreed to participate in the study and questioned them extensively about their health, caffeine consumption and other health habits. They found that even a typical cup of coffee a day may double the risk of miscarriage.

It is the first study to take nausea and morning sickness into consideration in determining the effects of caffeine. Most women who have morning sickness, and therefore likely have a healthy pregnancy at low risk of miscarriage, automatically cut back or eliminate coffee. This could have skewed previous test results as the women who felt well enough to continue coffee may naturally be at higher risk of miscarriage unrelated to caffeine. The latest report found a higher risk than was previously known.

Results showed that women who drank 2 or more 8 ounce cups of coffee (researchers estimated the amount of caffeine in 2 small cups of coffee to be about 200 mg of caffeine) per day (or about 5 servings of soda) had around double the risk of miscarriage compared to women who consumed no caffeine. But here is the rub – servings of coffee and latte’s are often super-sized like so many other fast-food drinks, and depending on the type of brewing, the caffeine content per serving could be much higher than is now thought safe. Other sources of caffeine such as tea, cola and other soft drinks, hot chocolate and even chocolate are also sources of caffeine – but much lower amounts. The increased risk of miscarriage appeared to be due to the caffeine itself, rather than other possible chemicals in coffee since caffeine intake from non-coffee sources such as caffeinated soda, tea and hot chocolate showed a similar increased risk of miscarriage in the study.

Caffeine has pharmacologic activity, is a major brain and body stimulant, and crosses easily through the placenta. Caffeine is more difficult for the fetus to metabolize and it also may decrease blood flow to the placenta as it constricts the blood vessels which supply the fetus with oxygen, blood and nutrients needed for survival.  It also speeds up the heart, raises blood pressure, and it may influence fetal cell development and even play some role in fertility and premature birth. A steady supply of caffeine to the fetus also increases the chances of caffeine withdrawal as well at birth.

I would suggest that all women who are pregnant or planning to be come pregnant taper off high caffeine beverages such as caffeinated coffee and black tea (no one should be drinking caffeine rich sodas with empty calories nor consuming enough dark chocolate to add to the miscarriage risk). Decaffeinated teas and coffees are probably safe, but still contain some caffeine. Drinking more fluids while pregnancy is important – try nutritional drinks such as milk, soy or rice milk, 100% fruit juices, hot chocolate and even chocolate milk (contains negligible amounts of caffeine).

If you are already getting a lot of caffeine, remember that tapering off the drinks will help prevent withdrawal symptoms of headache and jitteriness. But if you decide to go cold turkey, rest assured you WILL get over it and feel back to normal in a few days.

As always, I welcome your questions and comments on this or any other medical concern.

Warm regards,

Dr. Marie

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