The glow emanating from some pregnant women might dim if more of them take into account new research that links caffeine, to low birth rate babies and caffeine from coffee in particular to lengthened pregnancies. The research, published in BioMed Central's journal BMC Medicine, was conducted by a Norwegian team who included nearly 60,000 pregnancies, examined over a ten-year period, in the study.
A mother's placenta is an even better caffeine delivery system than a Starbucks drive-thru. However, developing embryos don't have the enzymes needed to inactivate it efficiently. For this reason, the WHO currently suggests a limit of 300 mg a day during pregnancy and some countries recommend only 200 mg, which is less than a single cup of Joe.
For the study, a team from the Norwegian Institute for Public Health examined all sources of caffeine consumed by the mothers including coffee, tea, soda and food made with cocoa. They found that caffeine from all sources reduced birth weight. An average-weight baby (7.94 pounds) lost between .74 -.63 ounces for each 100 mg of caffeine the mother consumed daily.
However, it wasn't just caffeine, but the source of caffeine, that mattered. Caffeine from all sources increased the length of the pregnancy by five hours per 100 mg caffeine per day, but caffeine intake from coffee was associated with an even longer gestational length - eight hours extra for every 100 mg caffeine per day. This association means that it is not just the caffeine in coffee which increases gestational length but either there must be a substance in coffee which is responsible for the extra time or there is a behavior associated with coffee drinking not present in women who drink only tea, for example.
Low birth weight babies are at higher risk of both short term and lifelong health problems. With these results revealing that even 200 to 300 mg of caffeine a day can increase the risk of a baby being born small for its gestational age, or SGA, by almost a third, caffeine-consumption recommendations for pregnant women may need to be reevaluated. Along with pants with non-elastic waistbands, coffee may be something women might give up during pregnancy.