What do medical sources say about Green Tea during pregnancy?

1st Trimester: NCCIH says green tea contains caffeine, and ACOG describes less than 200 mg a day as moderate caffeine intake during pregnancy; the NHS estimates about 75 mg in a cup of green tea. A 2022 review of tea, not green tea alone, did not find a statistically significant rise in neural tube defects, which affect the brain or spine. A 2012 study found no overall link between tea and spina bifida. Folate studies are mixed: a tea co-ingestion study found lower short-term folate levels, while pregnancy surveys did not consistently find lower folate. The European Commission requires some concentrated green tea extract products to carry a pregnancy warning because studies did not include pregnant people; its rule excludes water-based extracts comparable to traditional green tea infusions. Ask your provider about your situation.

What do medical sources say about Green Tea while breastfeeding?

NCCIH and LactMed report that caffeine can enter breast milk, and NHS says high amounts may make a baby restless or keep them awake. LactMed reports that very high maternal caffeine intake has been linked with infant fussiness, jitteriness, and poor sleep; a 1985 study of 11 mother-infant pairs found no change in sleep time or heart rate at 500 mg a day for five days. NHS lists 200 mg of caffeine a day while breastfeeding and gives a 38 mg estimate for one mug of green tea; its pregnancy page lists 75 mg per cup, so serving estimates differ. LactMed found no breastfeeding studies of oral green-tea extract, while the European Commission requires a lactation warning on some concentrated green tea extract products because studies did not include breastfeeding people or breastfed infants. Ask your provider about your situation.

Where do sources disagree on Green Tea in pregnancy or breastfeeding?

Tea, folate absorption, and pregnancy findings A 2008 human crossover study found lower short-term serum folate after folic acid was taken with green or black tea extract. A 2025 cell study found concentration-dependent inhibition of PCFT-mediated folate transport by green tea. A 2015 survey of pregnant women found no association between low-level tea intake and plasma folate. A 2025 EGCG trial in non-pregnant women found folate stayed within the normal range, although levels trended lower and one medication-combination group had a significant decrease. The studies tested different exposures and outcomes: one measured short-term folic acid levels after tea extract, one tested cells, one surveyed tea drinkers during pregnancy, and one tested a standardized extract in non-pregnant women. They were not head-to-head studies. Tea may affect short-term folic acid absorption, but the human pregnancy findings are mixed. The evidence does not establish that brewed green tea causes folate deficiency or birth defects.

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Green Tea

Herbal

Also called · 2 names▾

green tea extract, Camellia sinensis

Herbal supplement (tea and extract)

Herbs and supplements are not FDA-approved before sale. About these sources

Tea
Capsule/tablet
Topical

Pregnancy

Human outcome evidence is mostly about tea in general, not green tea alone. A 2022 systematic review and meta-analysis included 7 articles, 9 studies, 2,834 cases and 19,924 participants; it found no statistically significant increase in neural tube defects with periconceptional tea (OR 1.37, 95% CI 0.96-1.95, P=.08; PMID 35366455). In a 2012 case-control study of 518 spina bifida cases and 6,424 controls, overall tea intake was not associated with spina bifida; high-tea subgroups with more than 400 mcg folic acid had wide confidence intervals (OR 2.04, 95% CI 0.69-7.66, and OR 3.13, 95% CI 0.87-11.33; PMID 22641606). A 2008 randomized crossover study in healthy volunteers found lower serum folate Cmax and AUC after folic acid was taken with green or black tea extract; at 0.4 mg folic acid, green tea reduced mean Cmax by 39.2% and AUC by 26.6%. Its abstract does not state the number of volunteers (PMID 18551467). A 2015 cross-sectional study of 1,724 pregnant Chinese women found no association between low-level tea drinking and plasma folate; 55.2% of tea drinkers preferred green tea (PMID 26119069). A 2018 cross-sectional study of 2,701 pregnant Japanese women found negative associations between serum folate and caffeine and tannin intake, but it did not establish cause (PMID 29709887). A 2025 phase 1B trial randomized 39 non-pregnant, non-lactating women to 720 mg/day of EGCG for 30 days; 30 completed. Folate remained within the normal range, although group means trended lower and the EGCG-plus-clomiphene group had a significant decrease (PMID 40077973). A November 2025 cell study found green tea inhibited PCFT-mediated folate transport, with an IC50 of 6.1%; it used human PCFT-expressing cells, not pregnant people or pregnancy outcomes (DOI 10.1155/jfbc/1893592). A July 2025 case-control study associated five or more cups of tea per day with congenital anomalies (OR 3.21, 95% CI 1.05-10.80) among 150 cases and 150 controls; it did not identify green tea and used retrospective maternal reports and convenience sampling, so it is not a green-tea-specific result (PMID 40772092). A May 2026 rat study reported altered apoptosis markers in newborn rat heart cells after maternal green tea extract exposure; this is animal-only evidence and does not establish a human outcome (PMID 42195192).

Breastfeeding

LactMed says green tea leaves and stems contain caffeine, l-theanine, polyphenols and tannins. It states that no green tea components besides caffeine have been measured in milk after tea ingestion, and no breastfeeding studies were found for oral green tea extract. LactMed's separate caffeine record reports infant fussiness, jitteriness and poor sleep with very high maternal caffeine intake, and it describes Ryu's balanced crossover study of 11 mother-infant pairs: maternal caffeine at 500 mg/day for 5 days did not change infant sleep time or heart rate. NHS says caffeine can reach breast milk and may make a baby restless or keep them awake; it lists 200 mg/day while breastfeeding and estimates 38 mg in a mug of green tea. The European Commission's warning is for covered EGCG-containing green tea extract foods because intervention studies did not include breastfeeding women or breastfed infants. These caffeine studies do not directly test brewed green tea or green tea extract in breastfeeding people.

Tea, folate absorption, and pregnancy findings

Source A says: A 2008 human crossover study found lower short-term serum folate after folic acid was taken with green or black tea extract. A 2025 cell study found concentration-dependent inhibition of PCFT-mediated folate transport by green tea. (Alemdaroglu et al. 2008: Tea and folic acid pharmacokinetics, Narawa et al. 2025: Green tea and folate transport in cells)
Source B says: A 2015 survey of pregnant women found no association between low-level tea intake and plasma folate. A 2025 EGCG trial in non-pregnant women found folate stayed within the normal range, although levels trended lower and one medication-combination group had a significant decrease. (Liu et al. 2015: Tea and plasma folate in pregnant women, Johnson et al. 2025: EGCG and folate in reproductive-age women)
Why they differ: The studies tested different exposures and outcomes: one measured short-term folic acid levels after tea extract, one tested cells, one surveyed tea drinkers during pregnancy, and one tested a standardized extract in non-pregnant women. They were not head-to-head studies.
Other sources: A 2018 pregnancy cohort found negative associations between serum folate and caffeine and tannin intake. The European Commission notes that intervention studies did not include pregnant or lactating women; this is a data-gap statement, not a finding about the general-tea folate studies. (Otake et al. 2018: Folate and caffeinated beverages in pregnant women, Commission Regulation (EU) 2022/2340)
What the evidence shows overall: Tea may affect short-term folic acid absorption, but the human pregnancy findings are mixed. The evidence does not establish that brewed green tea causes folate deficiency or birth defects.

General tea and congenital anomaly findings

Source A says: A 2025 case-control study associated five or more cups of tea per day with congenital anomalies, but the exposure was tea generally, not green tea specifically. (Najafi et al. 2025: Maternal tea and congenital anomalies)
Source B says: A 2022 meta-analysis did not find a statistically significant increase in neural tube defects with tea, and a 2012 study did not support an overall tea-spina bifida association. (Yan et al. 2022: Tea consumption and neural tube defects, Yazdy et al. 2012: Maternal tea and spina bifida)
Why they differ: The studies used different populations and outcomes. The 2025 study was a small retrospective case-control study of several dietary exposures and all congenital anomalies; the earlier studies examined neural tube defects or spina bifida and general tea intake.
Other sources: NCCIH, ACOG and NHS do not assess the 2025 result as a green-tea-specific finding. The EU regulation addresses EGCG extract labeling and does not evaluate congenital outcomes from brewed tea. (NCCIH: Green Tea, ACOG Committee Opinion 462: Moderate Caffeine Consumption During Pregnancy, NHS: Foods to avoid in pregnancy, Commission Regulation (EU) 2022/2340)
What the evidence shows overall: The 2025 study is a signal about general tea at high intake, not evidence of a green-tea-specific effect. It does not resolve the mixed pregnancy evidence.

Caffeine guidance while breastfeeding

Source A says: LactMed describes 300 to 500 mg/day as a possible intake range for most mothers, while also citing a 200 mg/day limit used by European authorities. (LactMed: Caffeine)
Source B says: NHS recommends no more than 200 mg of caffeine per day while breastfeeding. (NHS: Breastfeeding and diet)
Why they differ: The pages present different limits and different levels of caution. The NHS page does not explain why it chose 200 mg/day; LactMed notes both a higher possible range and the European 200 mg/day limit.
What the evidence shows overall: The sources do not give one shared breastfeeding caffeine limit. NHS states 200 mg/day, while LactMed discusses a possible higher range for most mothers and also cites the European 200 mg/day level.

Caffeine-related infant symptoms and the controlled study

Source A says: LactMed reports fussiness, jitteriness and poor sleep in infants whose mothers had very high caffeine intake. (LactMed: Caffeine)
Source B says: In a balanced crossover study of 11 mother-infant pairs, maternal caffeine at 500 mg/day for 5 days did not change infant sleep time or heart rate. (Ryu 1985: Maternal caffeine and breastfed infants)
Why they differ: The symptom reports and the controlled study used different designs and exposure histories. The trial was small and short, so it could not rule out uncommon or longer-term effects.
Other sources: NHS and NCCIH also say high caffeine intake may cause restlessness or poor sleep in infants, while noting that responses vary. (NHS: Breastfeeding and diet, NCCIH: Green Tea)
What the evidence shows overall: Very high caffeine intake has been linked with symptoms in reports, but the small controlled study did not detect a sleep-time or heart-rate change. These data concern caffeine, not green tea itself.

NHS examples of caffeine in green tea

Source A says: The NHS pregnancy page estimates 75 mg in a cup of black or green tea. (NHS: Foods to avoid in pregnancy)
Source B says: The NHS breastfeeding page estimates 38 mg in a mug of green tea. (NHS: Breastfeeding and diet)
Why they differ: The pages use different serving labels and do not specify a shared brewing method or cup volume, so the reason for the difference is not stated.
What the evidence shows overall: Present these as page-specific examples, not a fixed caffeine amount for every cup of green tea.

Last reviewed 2026-10-16

Independent check 2026-10-16

Not yet clinician-reviewed

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