Green Tea In Pregnancy: Benefits & Side Effects

Green tea contains polyphenols, catechins, caffeine and tannins, all impacting the risks and benefits of its consumption during pregnancy.

All green tea contains caffeine, a stimulant that can adversely affect a baby’s growth and development. Some doctors advise a restriction of 200 mg^[1] of caffeine per day, while others say to avoid it completely.  Caffeine is associated with adverse^[2] maternal/fetal outcomes.

 A benefit of green tea is the high number of antioxidants it has in the form of beneficial polyphenols^[3] and catechins. Conversely, green tea also contains tannins, which may reduce absorption of nutrients like iron and folic acid. Nausea, one of the early signs of pregnancy, makes it harder to meet nutrient needs compounding absorption problems.

The safety of green tea in pregnancy depends on various factors including your healthcare provider’s recommendations regarding caffeine intake. Some providers allow for moderate consumption.

What Is Green Tea?

Green tea is made from the plant Camellia sinensis and is one of the least processed forms of tea with the highest levels of polyphenols and antioxidants. Although it comes from the same tea leaves as other teas, it undergoes a different form of processing^[4] involving steaming, pan frying, and drying. Green tea is processed from the same plant as black tea and is not considered herbal-based. 
Green tea and its constituents have been studied for their protective effects on heart disease and cancer,  relieving digestive distress, weight loss, alleviating headaches, and improving mental alertness, although research is inconclusive on most of its stated benefits^[5].

Can I Drink Green Tea While Pregnant?

Yes, you can drink green tea while pregnant if your doctor approves and you are not in your first trimester. However, research indicates that such tea^[6] should be consumed with caution. The development of liver disorders and gastrointestinal distress have been reported when green tea is consumed on an empty stomach.

Green tea also has a wide range of drug interactions^[7], so care should be taken when combining it with prescription drugs, and the advice of a healthcare professional should be sought. 

Green tea also contains caffeine. Some healthcare professionals may advise pregnant women to avoid caffeine entirely^[8] due to the potential risks of stillbirth, miscarriage, leukemia, and small-for-gestational-age births. Other health professionals suggest limiting caffeine from all sources (chocolate, coffee, tea) to 200 mg per day, so check with your doctor before adding green tea to your diet.
One cup of green tea contains about 29.4 mg of caffeine^[9], and decaffeinated tea may contain anywhere from 2 mg to 12 mg of caffeine^[10]. So, if your doctor advises you to avoid all sources of caffeine, know that even decaffeinated tea contains some caffeine.

Benefits of Green Tea During Pregnancy

While caffeine is the central concern in green tea, many benefits can be obtained from drinking this beverage during pregnancy.

Regulation Of Blood Pressure

The polyphenols in green tea stabilize blood pressure^[11], which may fluctuate during pregnancy. These effects are the result of antioxidant, anti-inflammatory and vascular reactions as well as gut microbiome influences.

Blood Sugar Control

The polyphenols found abundantly in green tea can reduce the risk for gestational diabetes. The anti-diabetic potential of polyphenols is rarely reported in the literature.

Polyphenols exhibit the following blood sugar control^[12] effects:

• Increasing glucose metabolism.
• Improving vascular function.
• Reducing insulin levels.
• Reducing HbA1C levels. HbA1C is a measurement of the average blood glucose over the past 2-3 months.

May Alleviate Mood Swings

Pregnancy is an emotional time as hormones shift to prepare for the new life growing inside. Polyphenol compounds present^[13] in green tea may affect depression, mood, behavior, cognition, and brain plasticity. Maternal depression is a common disorder and is associated with preterm birth, low birth weight, fetal growth restriction, and postnatal complications.

The CDC reports that about one in eight women experience^[14] depression during their pregnancy. So, anything that may help reduce the symptoms of this low mood will increase the woman’s quality of life and health outcomes for her unborn baby.

Resolves Some Skin Problems

The anti-inflammatory nature of green tea may help with bothersome itchiness from dry skin or skin irritations. Itching is common during pregnancy and is possibly related to a change in hormones or the development of stretch marks.

However, itchiness can also be caused by a condition that affects^[15] about one in every 140 pregnant women: intrahepatic cholestasis. This condition requires medical attention and is characterized by dark urine, pale bowel movements, yellowing of the skin and eyes, and itching that is worse at night.

Boosts Immunity

Polyphenols in green tea may have an immunomodulating effect on the pregnant woman’s immune system. Immunities are altered in pregnancy, and polyphenols may exert a protective^[16] effect on weakened immunities, making the woman less susceptible to infections.

Strengthens Bone Health

Bone metabolism is altered in pregnancy to support the growing fetus, with bone resorption occurring if calcium is insufficient in the diet. Hormonal changes can impair homeostasis in bone integrity, resulting in fragility. The greatest impact on bone mineral^[17] density is seen in women who choose to breastfeed.
Although further research is needed to understand the relationship, polyphenol-rich foods have been used to prevent the incidence and progression^[18] of osteoporosis. This suggests a favorable effect on bone metabolism that may positively enhance this process in pregnancy.

Risks Of Green Tea Consumption

Despite all the wonderful benefits associated with green tea consumption and its high levels of phenolic compounds, there are some downsides. Some of these risks include the following:

Decreased Absorption Of Some Nutrients

Tannins and catechins may bind to iron in the gastrointestinal tract, decreasing its absorption. Iron needs increase during pregnancy to 27 mg per day, and meeting these needs is often challenging. So, ingesting a compound that inhibits iron absorption is risky.

When the tannins bind the iron, the antioxidant capability of the tea^[19] is lost. The best way around this is not to consume green tea in conjunction with iron-rich foods. When you eat iron-rich foods, combine them with a natural source of vitamin C to enhance the absorption of this essential mineral.

Furthermore, the absorption of folic acid^[20] may be decreased by both catechins and tannins, making this an important consideration during the first trimester when the risk for neural tube defect is the highest. Pregnant women need 400 mcg of folic acid^[21] before and during pregnancy to prevent neural tube defects. Anything that impairs its absorption is risky during pregnancy, especially during the first 28 days after conception, when many women do not even know they are pregnant.

Catechins have not been associated^[22] with other adverse maternal or fetal outcomes.

Digestion Problems

Food inhibits the absorption^[23] of the polyphenol EGCG. However, if it is consumed on an empty stomach, stomach irritation may occur^[24], leading to nausea, increased acidity, and constipation. Drinking green tea 30-45 minutes before or after meals is usually the recommendation.

Caffeine Content

The World Health Organization advises^[25] a limit of 300 mg of caffeine daily while others advise a limit of 200 mg/day^[26] to reduce risks of pregnancy loss and low birth weight. However, more recent research challenges these limits saying that any caffeine at all^[27] increases the risks of pregnancy failure and poor maternal/fetal outcomes.
Caffeine at any point in pregnancy may cause epigenetic changes^[28] affecting the health of the offspring on into adulthood. Thus, it is important for your health care professional to weigh the pros and cons of the current research vs. the current guidelines when making recommendations to their pregnant patients regarding safe caffeine intakes.

Teas To Avoid During Pregnancy

Herbal teas may be risky to consume during pregnancy as not all herbs are safe during this time, especially during the first trimester. Herbal medicine is reported to be used by about 28% of pregnant women^[29] globally, and in some regions, such as India, the use may be as high as 70%. Current research suggests that^[30] red raspberry leaf, chamomile, fennel, peppermint, dong qui, goldenseal, and black cohosh may be associated with adverse maternal outcomes or toxicity from contaminants. 

Most other commonly used herbal teas are safe when used in moderation during the second and third trimesters. Always consult a health professional before adding any herbal preparation to a pregnancy diet.

Conclusion

Green tea consists of polyphenols, catechins, antioxidants, caffeine, and tannins. Some of these ingredients are beneficial to pregnancy, and others are risky, posing possible associations between their use and adverse maternal/fetal outcomes. The safety of green tea during pregnancy depends on the following: when your gestational consumption occurs, your healthcare provider’s recommendations on caffeine consumption, and your ability to absorb sufficient iron and folic acid despite malabsorption problems caused by the tannins.

Since current research challenges the 200 mg per day caffeine limitation guideline, such studies need to be considered when making safety recommendations to pregnant women. Until governmental and professional organizations formally revise the guidelines, it is left up to your doctor to decide on study interpretations for their patients.