Except for plain water, tea is the world's most widely-consumed drink. Although expectant mothers should avoid green tea, the National Institutes of Health consider moderate amounts of black tea safe for pregnant and nursing women. However, there are several situations where pregnant women should give up black tea entirely.

About Black Tea

Black tea is the most highly caffeinated of the teas prepared from the leaves of the tea plant, Camellia sinensis. It's also the most familiar tea to American consumers. In the United States, we drink black tea both hot and cold. Black tea is also the basis for Chai, a popular Indian drink spiced with cinnamon and cardamom.

Black Tea and Caffeine

Due to the long fermentation that's part of its processing, black tea contains the most caffeine of all the true teas, from 40 to 120 mg, depending on brand. Brigham Young University recommends that pregnant women limit their caffeine consumption to less than 300 mg daily, the equivalent of two or three 8-oz. cups of black tea. Other foods, including coffee, cola drinks and chocolate, contain caffeine as well, so take them into consideration when calculating your total daily intake.

Other Side Effects of Black Tea

The caffeine content isn't the only potential problem with black tea in pregnancy. Black tea is a natural diuretic and thus increases urine output, so if you have reached the stage in your pregnancy where you need to relieve yourself frequently, consider reducing your tea consumption. According to NIH, black tea can also cause sleep problems and raise your blood pressure. These are both common pregnancy complications, especially in the third trimester, so avoid drinking black tea if you develop these symptoms.

Black Tea Risks

If you're diabetic, be aware that black tea can increase your blood sugar levels and necessitate a change in your medication. Avoid black tea if you've developed pregnancy-related anemia, as black tea exacerbates anemia. And if your obstetrician is concerned about your calcium levels, you should stop drinking black tea, since caffeine depletes the body's calcium reserves.