On Nutrition

Caffeine, Coffee and Conception

DEAR DR. BLONZ: Does coffee consumption interfere with attempts to get pregnant? I am 25 years old, in very good health, with no serious health problems. I have two cups of coffee during the morning hours, but nothing more during the rest of the day. I am more than willing to cut back if needed. -- S.T., Tulsa, Oklahoma

DEAR S.T.: Coffee and caffeine represent an ongoing topic of discussion and debate, especially regarding their potential impact on pregnancy. Concerns include the fact that caffeine can cross the placenta, and that the developing fetus has not yet developed an ability to metabolize it as mom can.

In a healthy adult, the half-life of caffeine is about three to four hours; that is the time it takes the body to reduce the level found in the blood by half. In the case of caffeine, that process includes changing it into nonstimulating substances in preparation for elimination. Interestingly, caffeine’s half-life rises for pregnant women to about 15 hours during the last trimester.

As to your specific question, studies have offered evidence on both sides of the risk argument, with some concluding that it is possibly safe, others concluding the opposite. In a typical study, the process would be to take a large population of similar individuals, ordering them according to coffee/caffeine intake. The population would then be split into groups from the lowest to the highest levels of intake, and the incidence of the health issue being studied would be examined to see if it reveals a significant effect.

Here are some examples of the coffee-pregnancy conundrum. One study indicates that having more than three cups a day can significantly affect your ability to conceive, but another finds no such association. Which study to believe?

What about an association between coffee consumption and the risk of miscarriage? A study in the journal Epidemiology reported no increase in risk with intakes of up to 200 milligrams per day, which is what you might find in about two cups of coffee (depends, of course, on the strength of the brew). But there is also a study in the American Journal of Obstetrics and Gynecology reporting an adjusted hazard ratio of 1.42 for caffeine intakes up to 200 milligrams per day. (A hazard ratio of 1.0 means no effect; the higher the number, the more significant the effect.) For caffeine intakes of 200 milligrams or more per day, the hazard ratio was 2.23. And a study in the January 1998 issue of Archives of Diseases of Children found an association between heavy coffee drinking during pregnancy (defined as over four cups a day) and the risk of sudden infant death syndrome (SIDS).

There is little in the scientific literature condemning light consumption of coffee (up to one cup a day). But a couple things should always be kept in mind: that coffee is not essential for the health of your child, and that there is no guaranteed-safe level of intake. Science, after all, has made mistakes, and of all the stages in life, pregnancy is not the time to entertain avoidable risks. Seems reasonable to eliminate caffeine, or at least keep it to an absolute minimum, and err on the side of safety.

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

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