Is green tea safe during pregnancy?

In ordinary amounts, probably yes, and the evidence is indirect. We found no trial of green tea as a drink in pregnancy and no systematic review of it. The answer comes from caffeine and from catechins, the compounds sold in green tea supplements. A cup of brewed green tea has about 29 mg of caffeine in USDA data, and EFSA set 200 mg of caffeine a day as a safe level for the fetus. The open questions are tea around conception, because of folate, and high-dose green tea extracts.

Unsettled. Whether daily green tea around conception affects folate is not settled. One Chinese case-control study found women who drank tea daily had about 3 times the odds of a neural tube defect pregnancy, from only 20 cases and 9 controls who drank it daily. A Tokyo study found more green or oolong tea went with lower serum folate. A larger Chinese study found no difference. None of the three can show cause.

What the trials found

Caffeine, the part with a trial behind it

A Cochrane review found one usable randomized trial, and it was about coffee. In Denmark, 1,197 women who drank 3 or more cups of coffee a day were given caffeinated or decaffeinated instant coffee in the second and third trimester. Cutting caffeine by an average of 182 mg a day did not change birthweight, a mean difference of 20 g (95% CI -48.68 to 88.68). Preterm birth had a risk ratio of 0.81 (95% CI 0.48 to 1.37), which is not significant. The reviewers rated the evidence low quality, and the trial did not study miscarriage.

Observational data point the other way. An umbrella review of meta-analyses linked caffeine or coffee in pregnancy to 34% higher odds of low birth weight, an odds ratio of 1.34 (95% CI 1.14 to 1.57). It did not separate tea from coffee or give a dose threshold in the abstract, and odds from people who chose their own drinks are not the same as a risk caused by caffeine.

Folate, the question specific to tea

The concern is that tea catechins may interfere with folate, which protects against neural tube defects. In the Shanxi case-control study, 631 cases and 857 controls, daily tea around conception had an odds ratio of 3.1 (95% CI 1.4 to 7.0) against no tea, before adjustment. The raised odds held after the authors adjusted for folic acid supplements, age, education and occupation. So few women drank tea daily that the interval is wide, and the abstract does not say which tea.

In 254 pregnant women in Tokyo, higher intake of green or oolong tea went with lower serum folate after adjusting for folate intake and supplements. The abstract does not say whether anyone fell below the normal range. In 1,724 pregnant women in three areas of China, median plasma folate was 48.7 nmol/L in tea drinkers and 45.2 nmol/L in non-drinkers, with no statistical difference. Only 16.2% drank tea, mostly rarely, so that study says little about heavy drinkers.

In 39 women of reproductive age who were not pregnant, 720 mg of green tea extract EGCG a day for 30 days left folate in the normal range in everyone, including carriers of MTHFR or DHFR gene variants. Every group took EGCG, so there was no placebo to compare against.

Catechin supplements used as treatment

Two lines of research tested EGCG as a medicine in pregnancy, and they are about capsules. A 2025 systematic review of 14 trials in preeclampsia found one trial of 349 women where adding EGCG to nifedipine shortened the time to blood pressure control, a mean difference of -14.10 minutes (95% CI -18.46 to -9.74), on low-certainty evidence. In a double-blind trial in women with gestational diabetes in the third trimester, 404 were randomized to 500 mg EGCG a day or placebo until term. The authors report better glucose measures and fewer newborn complications, the abstract gives no effect sizes, and only 326 women finished. Neither result is a reason to take green tea extract in pregnancy.

Who should be careful

Not for everyone. Green tea extracts and catechin tablets are a different product from a cup of tea. EFSA found that 800 mg of EGCG a day or more taken as a food supplement raised liver enzymes in clinical trials. That finding is not specific to pregnancy. If you are pregnant or trying to conceive, ask whoever looks after your pregnancy before taking any green tea supplement.

If you are planning a pregnancy, the folate question is the one to take seriously. The single study that found higher odds of neural tube defects concerned daily tea around conception, and the result held after adjusting for folic acid use. The studies of folate levels disagree, so this stays an open question rather than a rule.

Iron is the other consideration. Pregnancy raises the need for iron, and tea polyphenols reduce its absorption. In a meta-analysis of 34 randomized trials outside pregnancy, polyphenol supplements lowered serum iron by 13.72 ug/dL (95% CI -20.74 to -6.71) without a significant change in ferritin. That is indirect evidence, from supplements in people who were not pregnant. If your iron is low, mention your tea habit to whoever looks after your pregnancy.

The 200 mg ceiling is a total for the day, and coffee counts toward it as well as tea. In the USDA data, decaffeinated green tea has none.

What expert bodies say

The Nordic Nutrition Recommendations 2023 advise pregnant women not to exceed 200 mg of caffeine a day, the level EFSA set as safe for the fetus. We could not open the EFSA opinion itself and cite it through the Nordic review. The American College of Obstetricians and Gynecologists says caffeine below 200 mg a day does not appear to be a major factor in miscarriage or preterm birth. EFSA's panel on green tea catechins tied raised liver enzymes to supplements at 800 mg EGCG a day or more. None of these bodies addresses green tea and pregnancy directly.

For a pregnant woman, a few cups of ordinary green tea a day fits within the caffeine ceiling. Extracts are where the clearest caution lies, and daily tea around conception stays an open question because of folate. More on the drink is on the green tea page.

How we searched

What would change this answer

• A prospective cohort that records green tea around conception and follows neural tube defects in a population where folic acid is fortified or routinely taken. One case-control study with 20 exposed cases is a reason for caution and too little to set a limit.
• Pregnancy outcomes from the FRIEND trial of EGCG in women with fibroids trying to conceive. It is the nearest thing to a safety test of catechins around conception.
• Any trial of green tea as a drink in pregnancy. We found none, and no systematic review of green tea in pregnancy.

Sources

1. ev-gtpg-01 · Meta-analysis or systematic review · Cochrane systematic review of randomized controlled trials · n = 1,197
   Caffeinated instant coffee (568 women) was compared with decaffeinated instant coffee (629 women) and it was found that reducing the caffeine intake of regular coffee drinkers (3+ cups/day) during the second and third trimester by an average of 182 mg/day did not affect birthweight (g) (mean difference (MD) 20.00, 95% confidence interval (CI) -48.68 to 88.68; one study, 1197 participants; low quality evidence), preterm birth (risk ratio (RR) 0.81, 95% CI 0.48 to 1.37; one study, 1153 participants; low quality evidence) or small-for-gestational age (RR 0.97, 95% 0.57 to 1.64; one study, 1150 participants).
   
   Who: regular coffee drinkers (3+ cups/day) in the second and third trimester, caffeinated vs decaffeinated instant coffee
   Effect: birthweight MD 20.00 g (95% CI -48.68 to 88.68); preterm birth RR 0.81 (0.48 to 1.37); small-for-gestational age RR 0.97 (0.57 to 1.64); low quality evidence
   Certainty: A single Danish RCT with coffee, not tea; low quality by GRADE. The authors: evidence is insufficient to confirm or refute a benefit of giving up caffeine. Miscarriages not studied.
   Cochrane Database of Systematic Reviews, 2015, CD006965 (Jahanfar and Jaafar), Effects of restricted caffeine intake by mother on fetal, neonatal and pregnancy outcomes · checked 2026-10-07 · we read the abstract
2. ev-gtpg-02 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 14 trials; EGCG outcome 1 trial, 349 women
   In women with preeclampsia, the addition of epigallocatechin gallate (EGCG) to nifedipine may reduce the time needed to achieve blood pressure control (mean difference (MD) = -14.10 min, 95% CI -18.46 to -9.74) and increase the time to the next hypertensive crisis (MD = 3.10 h, 95% CI 2.35 to 3.85) compared to nifedipine alone (1 trial, 349 women; low certainty).
   
   Who: women with preeclampsia in randomized controlled trials of polyphenol-containing products
   Effect: time to BP control MD -14.10 min (95% CI -18.46 to -9.74); time to next hypertensive crisis MD +3.10 h (2.35 to 3.85); low certainty
   Certainty: EGCG supplement as a drug together with nifedipine, not tea. One RCT. Authors: evidence on benefit and adverse effects is limited and uncertain.
   BJOG, 2025 · checked 2026-10-07 · we read the abstract
3. ev-gtpg-03 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 34 RCTs
   Polyphenol supplementation had an inhibitory effect on the SI concentration (-13.72 μg/dL; 95% CI: -20.74, -6.71) and TS (-3.10%; 95% CI: -4.93, -1.27), with no effect on ferritin (-9.34 ng/mL; 95% CI: -28.55, 9.87).
   
   Who: participants in randomized controlled trials of dietary polyphenol supplementation
   Effect: serum iron -13.72 ug/dL (95% CI -20.74 to -6.71); transferrin saturation -3.10% (-4.93 to -1.27); ferritin -9.34 ng/mL (-28.55 to 9.87, not significant)
   Certainty: Indirect: not pregnant women and not green tea as a drink. Relevant because iron need in pregnancy is high; no effect on stores (ferritin).
   Am J Clin Nutr, 2021 · checked 2026-10-07 · we read the abstract
4. ev-gtpg-04 · Randomized controlled trial(s) · randomized controlled trial · n = 404 randomized (326 completed)
   After exclusion, 404 patients were randomly assigned into EGCG and placebo study groups and subsequently administered either 500 mg of EGCG or placebo, respectively, on a daily basis until full term.
   
   Who: pregnant women during their third trimester diagnosed with GDM
   Effect: 500 mg EGCG daily vs placebo: improved maternal diabetic parameters and fewer neonatal complications (no effect sizes in abstract)
   Certainty: Large dropout (176 and 150 completed). Abstract without effect numbers. A single study, not replicated. A supplement, not tea.
   J Hum Nutr Diet, 2017 · checked 2026-10-07 · we read the abstract
5. ev-gtpg-05 · Observational data · umbrella review of meta-analyses of observational studies · n = 13 systematic reviews, 15 meta-analyses
   The following 13 maternal factors were identified as risk factors for low birth weight: crack/cocaine (odds ratio [OR] 2.82, 95% confidence interval [CI] 2.26-3.52), infertility (OR 1.34, 95% CI 1.2-1.48), smoking (OR 2.00, 95% CI 1.76-2.28), periodontal disease (OR 2.41, 95% CI 1.67-3.47), depression (OR 1.84, 95% CI 1.34-2.53), anemia (OR 1.32, 95% CI 1.13-1.55), caffeine/coffee (OR 1.34, 95% CI 1.14-1.57), heavy physical workload (OR 1.87, 95% CI 1.00-3.47), lifting ≥ 11 kg (OR 1.59, 95% CI 1.02-2.48), underweight (OR 1.79, 95% CI 1.20-2.67), alcohol (OR 1.23, 95% CI 1.04-1.46), hypertension (OR 3.90, 95% CI 2.73-5.58), and hypothyroidism (OR 1.40, 95% CI 1.01-1.94).
   
   Who: pregnant women in meta-analyses of cohort, case-control and cross-sectional studies
   Effect: caffeine/coffee and low birth weight: OR 1.34 (95% CI 1.14 to 1.57)
   Certainty: Observational data, OR, not risk. Caffeine in general, without separation into tea and coffee, no dose threshold in the abstract.
   BMC Pregnancy Childbirth, 2024 · checked 2026-10-07 · we read the abstract
6. ev-gtpg-06 · Observational data · scoping review of systematic reviews for dietary guidelines · n = —
   Pregnant women should not exceed the recommended daily dose of caffeine intake of 200 mg set by the European Food Safety Authority as a safe level for the fetus.
   
   Who: pregnant women, Nordic and Baltic dietary guidelines
   Effect: caffeine ceiling 200 mg/day in pregnancy (EFSA)
   Certainty: EFSA 2015 figure; EFSA's own opinion could not be opened (Wiley 403), so we cite via NNR.
   Food Nutr Res, 2024 · checked 2026-10-07 · we read the abstract
7. ev-gtpg-07 · Position of an expert body · clinical practice guideline · n = —
   Moderate caffeine consumption (less than 200 mg per day) does not appear to be a major contributing factor in miscarriage or preterm birth.
   
   Who: pregnant women, ACOG Committee Opinion No. 462
   Effect: <200 mg/day caffeine: not a major contributing factor in miscarriage or preterm birth; growth restriction undetermined
   Certainty: 2010, ACOG later reaffirmed the position. The link with growth retardation and high doses was left open.
   Obstetrics and Gynecology, 2010, 116(2 Pt 1):467-468, ACOG Committee Opinion No. 462: Moderate caffeine consumption during pregnancy · checked 2026-10-07 · we read the abstract
8. ev-gtpg-08 · Observational data · food composition database · n = —
   Tea, hot, leaf, green, FNDDS code 92303010, fdc_id 2710490: Caffeine 12 MG per 100 g; 1 cup 240 g, 28.8 MG
   
   Who: USDA FNDDS 2021-2023, food code 92303010, Tea, hot, leaf, green
   Effect: caffeine 12 mg/100 g; 1 cup (240 g) 28.8 mg; decaffeinated 0 mg
   Certainty: A single mean value; brew strength and variety change caffeine severalfold. The 7-cup calculation is ours, not from the set.
   USDA FNDDS 2021-2023, food code 92303010, Tea, hot, leaf, green (fdc_id 2710490) · checked 2026-10-07 · we read the dataset
9. ev-gtpg-09 · Observational data · case-control study · n = 631 cases, 857 controls
   Compared with women who did not drink tea during the periconceptional period (487 cases and 688 controls), women who drank tea daily (20 cases and 9 controls) had a 3-fold increased risk (odds ratio = 3.1 [95% confidence interval = 1.4-7.0]) of having an NTD-affected pregnancy.
   
   Who: NTD cases and term controls in 4 rural counties of Shanxi Province, northern China, 2002-2007
   Effect: daily tea vs none: OR 3.1 (95% CI 1.4 to 7.0); adjusted OR 3.4 (1.4 to 8.3)
   Certainty: Only 20 cases and 9 controls drank tea daily, so the interval is wide. The type of tea is not given in the abstract. Mechanism: catechins inhibit dihydrofolate reductase.
   Epidemiology, 2011 · checked 2026-10-07 · we read the abstract
10. ev-gtpg-10 · Observational data · cross-sectional study · n = 254
    A multiple regression analysis revealed the high consumption of green tea or oolong tea to be associated with a low serum folate level during pregnancy, after adjusting for confounding variables including dietary folate intake and use of folic acid supplements or multivitamins (β = -0.131, p = 0.016).
    
    Who: healthy women with a singleton pregnancy at a prenatal clinic in metropolitan Tokyo
    Effect: high green or oolong tea (>57.3 mL per 1,000 calories): beta -0.131, p = 0.016 for serum folate
    Certainty: Small sample, single cross-section. Whether folate fell below normal, the abstract does not say.
    Biosci Trends, 2010 · checked 2026-10-07 · we read the abstract
11. ev-gtpg-11 · Observational data · cross-sectional study · n = 1,724
    The median of plasma folate concentration was 48.7 nmol/L in women who drank tea while it is 45.2 nmol/L in women who did not drink tea, with no statistical difference.
    
    Who: pregnant women during early second trimester in three cities/counties in China, 2011-2012
    Effect: median plasma folate 48.7 nmol/L (tea) vs 45.2 nmol/L (no tea), no statistical difference
    Certainty: Only 16.2% drank tea, mostly rarely. The authors limit the conclusion by the low level of consumption.
    Birth Defects Res A Clin Mol Teratol, 2015 · checked 2026-10-07 · we read the abstract
12. ev-gtpg-12 · Observational data · randomized open-label study without a placebo arm · n = 39
    During the intervention with EGCG, folate levels remained in the normal range in all subjects.
    
    Who: women aged 18 to 40 years, with or without uterine fibroids, not pregnant
    Effect: folate within normal range in all subjects during 30 days of EGCG 720 mg/day
    Certainty: All three groups received EGCG, so there is no comparison with placebo. Not pregnant. The accompanying publication (36678191, 800 mg) showed no signs of liver damage.
    Clin Transl Sci, 2025 · checked 2026-10-07 · we read the abstract
13. ev-gtpg-13 · Position of an expert body · EFSA ANS Panel scientific opinion · n = —
    Based on the available data on the potential adverse effects of green tea catechins on the liver, the Panel concluded that there is evidence from interventional clinical trials that intake of doses equal or above 800 mg EGCG/day taken as a food supplement has been shown to induce a statistically significant increase of serum transaminases in treated subjects compared to control.
    
    Who: adults in the EU consuming green tea infusions or green tea catechin food supplements
    Effect: 800 mg EGCG/day or more as a supplement: statistically significant increase in serum transaminases
    Certainty: Not about pregnancy separately. Important for green tea extracts and pills, not for brewed tea.
    EFSA Journal, 2018, 16(4):5239, Scientific opinion on the safety of green tea catechins (EFSA ANS Panel) · checked 2026-10-06 · we read the abstract