Caffeine and Pregnancy. How much is too much?

Last week news shows such as Today announced results from a recent study from the National Institute of Child Health and Human Development that associates caffeine consumption with early pregnancy loss. Headlines stated “drinking three or more caffeinated beverages a day raised the risk of early pregnancy loss.”  These headlines further confuse the already confusing question about how much caffeine intake is “okay” if you are trying to conceive or already pregnant.

The study published in Fertility and Sterility followed 344 expectant couples and examined lifestyle factors and the rate of early pregnancy loss. The study measured the number of caffeinated beverages partners drank as well as multivitamin use before they conceived through the seventh week of pregnancy. Researchers concluded that drinking three or more caffeinated beverages a day (before conception or during pregnancy) raised the risk of early pregnancy loss by 74 percent. Male preconception consumption of caffeinated beverages was found to be just as strongly associated with pregnancy loss as females.  The study however found that if a woman took multivitamin while she was trying to become pregnant through the first seven weeks of pregnancy  there was nearly a 80 percent reduction in the risk of miscarriage.

The study however only looked at an association, meaning it doesn't prove a cause and effect relationship.  It does not prove that caffeine intake itself leads to miscarriage. Another limitation is that the study examined the number of caffeinated beverages rather than measure total caffeine intake.  Caffeine content of caffeinated beverages can vary wildly between beverages. Nor did the study control for other confounding factors (exercise, sleep, or recreation drug use).  Individuals who drink more then 3 cups of coffee a day may be different that those who do not drink coffee. If these factors are not controlled for results can be misleading. For instance, high caffeine drinkers may have higher levels of subjective stress with poorer sleep habits etc. which may contribute to fertility loss.  Cigarette smoking, alcohol consumption, and a less health conscious lifestyle have all been linked to increased coffee consumption .

A previous 2011 systematic review  published in Birth Defects Research Part B of Developmental and Reproductive Toxicology  examined  both human and animal studies and  he risk of spontaneous abortion from caffeine exposure. They  concluded there was fair to good evidence that consumption of caffeinated beverages during pregnancy at a level ≤5 to 6 mg/kg body weight/day does not increase the risk of spontaneous abortion. Very very high caffeine intake in some animal studies demonstrates some increased risk however woman drinking  over a dozen cups of coffee in a day would not approach this level of caffeine intake.

Previous publications report an association between caffeine use in pregnancy and low birth weight and preterm birth.  For instance a  2014 meta-analysis of 100,000+ women reported that increases in maternal caffeine intake during pregnancy is associated with increased risk of delivering low birth weight infants (in a dose dependent manner).  However a randomized double blind trial that analyzed the effect of reducing caffeine intake found no effect on birth weight or preterm  birth when caffeine intake was decreased by 50% in women drinking 3+ cups a day prior to study enrollment. A 2010 systematic review similarly did not demonstrate a significant association between maternal caffeine intake anytime in pregnancy and preterm birth.

Given the knowledge of literature the American College of Gynecology states there is insufficient evidence to support reducing caffeine use below 200mg/day.

For hopeful or expecting mothers the first step is to determine how much caffeine you are consuming.  Caffeine is most associated with coffee, tea, soft drinks, and energy drinks. Content and can vary dramatically between products and brands.  For example the same size coffee at Starbucks has double the caffeine content compared to McDonalds. 

Caffeine can be also be present in unexpected places such some prescription and over the counter medications such as those for flu/cold, allergy, and headaches as well as diet pills and diuretics.   Caffeine content of popular items can be found here.

Dr. Williams of the Albert Einstein College of Medicine and a spokesman for the American College of Obstetricians and Gynecologists  warns " what I do end up seeing not infrequently, an effort to really be as thorough as possible, a lot of women will go cold turkey on caffeine. And what ends up happening is invariably these women will then develop rebound headaches and take medications to treat the headaches. Those medications may be harmful.”

If you decide to cut caffeine “cold turkey” you may experience withdrawal symptoms such as headache, anxiety/irritability, constipation/diarrhea, low mood, low energy, sweating, or shakiness. Most symptoms dissipate in few days but can last as long as two weeks for heavy drinkers. Gradually decreasing caffeine content over 1-2 weeks can minimize the risk of withdrawal symptoms. Strategies for decreasing caffeine content include transitioning to decaf, switching out tea for coffee, or drinking tea with a lower caffeine content.