How you process caffeine matters most in pregnancy

If you are anything like me, your day does not start until you've finished your first cup of coffee. I am famous for saying, "I am not awake yet!" until I've downed that first warm cup'o'joe. Despite everyone's love of coffee, when they are pregnant, many women worry about the effects of caffeine on their baby. Prior research shows that most of us continue to drink coffee during pregnancy; 75-90% of pregnant women and their fetuses are exposed to caffeine during pregnancy. One complication of pregnancy that has been studied in conjunction with caffeine is severe preeclampsia, a dangerous complication that includes high blood pressure, possible organ damage, and, if it progresses, seizures. The October 2015 Green Journal features an article exploring the relationship between caffeine and severe preeclampsia.

Dr. Eichelberger and her colleagues from the University of South Carolina-Greenville School of Medicine and other nearby hospitals collected blood samples in the second trimester from 33 women who later went on to develop severe preeclampsia and 99 women who had healthy pregnancies. When the body processes caffeine from the diet, 80% of it is turned into a substance called paraxanthine. The interesting thing about paraxanthine is that is allows scientists to get an idea of your caffeine over time instead of at a single moment. Prior research has shown that paraxanthine is the best marker for "steady-state" or long term caffeine intake. Using paraxanthine allowed the authors to measure how much caffeine a pregnant woman was drinking over time during her pregnancy.

But the researchers didn't stop there! Instead of just looking at how much caffeine mothers-to-be were drinking, they also looked at how fast their bodies were processing the caffeine. The enzyme that helps you metabolize caffeine into paraxanthine is called CYP1A2. During pregnancy, CYP1A2 is the main controller of caffeine metabolism. To measure the subjects' CYP1A2 activity, the researchers simply measured a ratio of paraxanthine levels to caffeine levels. If you are a fast metabolizer, you will have a high ratio. If you are a slow metabolizer, you will have a low ratio.

After measuring the paraxanthine and ratios in the womens' blood samples, the authors compared the two groups: women who developed severe preeclampsia versus women with healthy pregnancies. First, they compared the paraxanthine levels to see if the amount of caffeine women drank influenced their risk of preeclampsia. It did not. Women with healthy pregnancies did not have more caffeine intake than women with severe preeclampsia. In fact, the women with severe preeclampsia had lower levels of caffeine than the healthy women.

Now on to the even more exciting findings: women with healthy pregnancies metabolized caffeine faster. The higher your metabolism of caffeine, the more you were protected against severe preeclampsia. CYP1A2 efficiency testing is not ready for the prime-time, but perhaps in the next few years, we'll start to see even more advances in the way we council women on the risks of caffeine and pregnancy and possibly even test their metabolism. For now, I'm going to keep drinking my daily cup!