Conventional teas, including black, green, white and oolong varieties, derive from the leaves of the Camellia sinensis plant. Other forms of "tea," known as herbal teas, do not contain any tea leaves. Instead, they contain a combination of botanical products brewed in water. Although most common forms of tea are safe for moderate use during pregnancy, several ingredients should be avoided or restricted.
Caffeinated Teas
All forms of tea derived from the tea plant contain some amount of caffeine. According to the March of Dimes, brewed tea contains roughly 48 mg of caffeine per 8 oz. serving, while instant teas contain 26 to 36 mg of the stimulant in each cup. The March of Dimes advises expectant mothers to limit their intake of tea to keep total caffeine intake below 200 mg daily. If brewed tea is the only source of caffeine in a pregnant woman's diet, she can safely drink up to four 8 oz. cups of the beverage each day. Higher amounts could increase the risk of miscarriage and other complications.
Nettle
Stinging nettle leaf is included in many commercially available "pregnancy teas," recommended as a general tonic to relieve common discomforts and complications associated with pregnancy. Despite its popularity, nettle might pose a threat to a pregnant women or their unborn children. The American Pregnancy Association identifies nettle's status as "likely unsafe," hypothesizing that different parts of the plant might be dangerous, while others might be beneficial. Until more evidence is available regarding the safety of nettle during pregnancy, it is best for expectant mothers to avoid it.
Alfalfa
Alfalfa contains a high concentration of vitamin K, which is utilized in the prevention of postpartum hemorrhage and neonatal vitamin K deficiency. Alfalfa exists as an ingredient in many specialty teas designed for use in pregnancy. According to the National Institutes of Health, alfalfa teas are "possibly unsafe" for pregnant women because they might alter levels of the reproductive hormone estrogen. In theory, these hormonal effects could jeopardize the viability of a pregnancy or disrupt a developing fetus's endocrine system.
Red Clover
Herbalists occasionally recommend red clover tea as a fertility aid or pregnancy tonic, but pregnant women should generally avoid all teas containing red clover blossom or leaf. The University of Maryland Medical Center explicitly urges pregnant and nursing mothers to abstain from the use of red clover, noting that it has been linked to infertility in animals. As a general rule, pregnant women should not use any herbal teas containing hormone-altering compounds, since they can harm the health of both the mother and unborn child.
