(Female, 37) A: You can be absolutely sure that billions of cups of tea have been drunk by pregnant women! That said, there is also a basic principle of avoiding drugs during pregnancy, which would include avoiding stimulants such as caffeine in excessive quantity. The amount of caffeine in tea depends on the type of tea, the strength that you make it and how much you drink. Green tea contains caffeine. Jasmine tea is usually jasmine blended with black tea and so it also contains caffeine (unless specified). Although there are no known long-term harmful effects on a foetus, caffeine does cross the placenta so it is wise to avoid large quantities of caffeine – tea or coffee – while you are pregnant.