Pregnant Women and Coffee

“Coffee, for many of us, is a daily fix. But few would relate to it as being a life changer” – this is what BBC (27th Feb, 2013 issue) writes by narrating a story of Nepali farmer whose life was changed by farming coffee instead of regular maize and paddy cultivation. Nepalese coffee is different from other countries. People mainly produce Arabica type of coffee which is organic. But, what about intake of coffee by Nepalese women? Frankly, in Nepal tea is preferred than coffee. Most of the people in the rural area take milk-added-tea which is considered more harmful than black tea. Let’s know something about caffeine, a key component in coffee and its effect on the pregnant women.

Caffeine is a natural component of coffee, tea, and cocoa products. It is added to many soft drinks and to certain prescription and over-the-counter medications. Caffeine's pharmacologic effects include central nervous system stimulation, bronchodilation, and higher blood pressure, most likely through antagonism of adenosine receptors in the brain, heart, lungs, and blood vessels. Based on a recent survey by the U.S. Department of Agriculture, coffee, soft drinks, and tea (in that order) are the major sources of caffeine among adults. Average caffeine intake is estimated to be 164 mg per day among women 18–34 years and 125 mg per day among pregnant women. In a prospective cohort study conducted in Connecticut during 1988–1992, caffeine consumption during the first month of pregnancy was reported by 60% of study participants, with 16% consuming 150 mg or more of caffeine per day.

Caffeine is teratogenic in animal studies when administered at high concentrations. There is no evidence to support a teratogenic effect of caffeine in humans. Current epidemiologic evidence is not adequate to assess the possibility of a small change in risk of congenital anomalies resulting from maternal caffeine consumption.

Picture from Google on 16th June 2017 

Marilyn Brown has published a review paper in epidemiology journal by evaluating methodological aspects of epidemiologic studies of maternal caffeine exposure and risk of congenital anomalies1. He has reported that there is no evidence that caffeine intake causes a large increase in the risk of various types of congenital anomalies, but there is greater uncertainty about small elevations in risk. Given the relatively high prevalence of maternal caffeine exposure, even a small increase in the risk of congenital anomalies would have an important effect on public health. 

Large study populations and improved exposure assessment methods would be necessary to rule out small risks for specific categories of congenital anomalies after maternal exposure to caffeine.

In the United States, some 60 percent of women continue to drink caffeinated coffee during their first month of pregnancy.  About 16 percent of pregnant mothers consume 150 mg of caffeine or more per day. But the question is, Is this harmful to your unborn baby? Three things to know.  One, caffeine can freely cross the placenta.  Two, 90 percent of a mother’s caffeine level reaches the developing fetus.  Three, the half-life of caffeine is much longer in the fetus than in the adult2.

Some studies have shown a correlation between prenatal caffeine consumption and decreased birth weight.  But are there longer-term consequences? Researchers in Florida studied mice that had were exposed to physiologically relevant doses of caffeine in utero.  They found that caffeine significantly altered the expression of genes in embryonic hearts.  Pathways related to cardiovascular development and diseases were significantly affected by caffeine. The researchers stress that “the long-term effects of caffeine on human cardiac function are unclear.”  They recommend further studies “to evaluate the safety of caffeine exposure during human pregnancy.”

References

1.         Browne, M. L., Maternal exposure to caffeine and risk of congenital anomalies: a systematic review. Epidemiology 2006, 17 (3), 324-331.

2.         Fang, X.; Mei, W.; Barbazuk, W. B.; Rivkees, S. A.; Wendler, C. C., Caffeine exposure alters cardiac gene expression in embryonic cardiomyocytes. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 2014.