Is Caffeine Safe during Pregnancy?

updated April 1, 2015

Published in the January issue of The American Journal of Obstetrics and Gynecology, a study lead by Dr. De-Kun Li claims that pregnant women who take in more than 200 milligrams of caffeine a day (roughly two cups of coffee or five cans of soda) face a 40 percent rate of miscarriage.

The Facts

In this study, Dr. Li, a reproductive and perinatal epidemiologist at Kaiser Permanente Division of Research in Oakland, California, and her team monitored a total of 1063 pregnant women with an average pregnancy length of 71 days.  Participants were interviewed about their normal caffeine intake once at the beginning of the study, at which point 102 of the women had already miscarried.  Seventy more women suffered miscarriages during the remainder of the study.  Of the patients studied, women who drank no caffeine showed a 12.5 percent rate of miscarriage, while women who consumed roughly 200 milligrams of caffeine daily showed a miscarriage rate of 24.5 percent.

The Opposition

While these numbers may seem to overwhelmingly tip the scales against caffeine, many experts take issue with the accuracy of Dr. Li's study.  One of the major factors encouraging doubt in Dr. Li's results is that 80 percent of miscarriages are attributed to genetic abnormalities, on which caffeine would have no effect.  In fact, aside from chromosomal abnormalities, the most common causes of miscarriage are smoking, a mother's advanced age, and infections.  This study did not examine the miscarried fetuses to determine the actual cause of miscarriage, so it is not accurate to attribute all of these losses to caffeine.  Furthermore, more than half of the reported miscarriages occurred before the study even commenced, so it is nearly impossible to attribute those miscarriages to any one cause.

Other discrepancies in Dr. Li's study have to do with the fact that the women's caffeine intake was not watched or regulated for the duration of the study, but rather reported once at the inception of the study.  It is impossible to know whether all of the women in the study accurately reported how much caffeine they ingested, especially with the variety of cup sizes and caffeine levels available to today's consumers.  Furthermore, studies show that women who experience morning sickness have a lower risk of miscarriage.  Opponents to Dr. Li's findings argue that women who feel nauseated probably have no desire to drink caffeinated beverages, so this could also skew Dr. Li's results.

The Logic

Many studies have highlighted the dangers caffeine can pose to a fetus.  Indeed, caffeine ingested by a pregnant woman crosses the placenta into her fetus, whose underdeveloped metabolic system cannot efficiently process the chemical.  This could affect the baby's cell development, and it may also constrict the flow of blood to the placenta.  Caffeine intake by expecting mothers has also been linked to low birth weights and smaller head circumferences in newborns.

While excessive caffeine intake amongst pregnant women has been shown to have deleterious affects on developing babies, many doctors assure women that they don't have to eschew caffeine altogether.  In another study published in January, in the journal Epidemiology, researchers claim that two cups of coffee a day during pregnancy is a perfectly save level of caffeine.  The key here, say many experts, is moderation.  While it is not a good idea to keep the pot brewing all day and night, there is little evidence that a morning cup of joe or the occasional soda will harm the development of a fetus.

What Say You?

Though I am by no means an expert in either medicine or childbearing, I am of the opinion that, as women have been having children for thousands of years and in all imaginable conditions, human pregnancy is not as vulnerable as some would have us believe.  Still, I believe that pregnant women have a responsibility to provide the safest atmosphere possible for their developing babies.  This means that they should do away with all alcohol, cigarettes, and other drugs that have been proven to impede development, and they should observe healthy diet and exercise habits.  If you feel that you simply cannot live without your morning cup of coffee, most evidence says that it's safe.  But do you really want to risk it?  Why not just switch to decaf for nine months and clear your conscience?