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Is tuna safe to eat during pregnancy?

Yes, if you pick the kinds that are low in mercury and keep to the amounts agencies advise. The US Food and Drug Administration and the Environmental Protection Agency advise 8 to 12 oz of lower-mercury seafood a week in pregnancy, list canned light tuna as a Best Choice and bigeye tuna as a choice to avoid. The strongest evidence for eating fish at all is a Cochrane review of 70 randomized trials in 19,927 pregnant women: omega-3 fats, mostly as capsules, cut preterm birth from 13.4 to 11.9 percent. Nobody has run a trial of tuna itself in pregnancy.

Not for everyone. Tuna is a fish where the species changes the answer. In the US chart, canned light tuna, skipjack included, is a Best Choice, albacore and yellowfin are Good Choices, and bigeye has the highest mercury and sits on the list to avoid. One serving in that chart is 4 oz.

Women who gave birth early, percent
051015Preterm birth before 37 weeks, no omega-326 RCTs, 10,304 women13.4Preterm birth before 37 weeks, no omega-3: 13.4 percent (95% CI 13.4 to 13.4)Preterm birth before 37 weeks, omega-3same trials11.9Preterm birth before 37 weeks, omega-3: 11.9 percent (95% CI 11.9 to 11.9)Early preterm birth before 34 weeks, no omega-39 RCTs, 5204 women4.6Early preterm birth before 34 weeks, no omega-3: 4.6 percent (95% CI 4.6 to 4.6)Early preterm birth before 34 weeks, omega-3same trials2.7Early preterm birth before 34 weeks, omega-3: 2.7 percent (95% CI 2.7 to 2.7)

Raw proportions from the Cochrane review, so no interval is drawn on the bars. The omega-3 came mostly as capsules, and some trials used foods such as fish. Tuna itself was not tested. Source: card ev-tnpr-01 below.

What the trials found

The only A-level evidence here is about omega-3 fats, given as supplements or as foods such as fish. In the Cochrane review, preterm birth before 37 weeks had a risk ratio of 0.89 (95% CI 0.81 to 0.97) across 26 trials in 10,304 women, on high-quality evidence. Early preterm birth before 34 weeks fell from 4.6 to 2.7 percent, a risk ratio of 0.58 (0.44 to 0.77). The same review found very few differences in child cognition or IQ, on low to very low quality evidence. Most of those trials gave capsules, so the result speaks for omega-3 and only indirectly for a tuna sandwich.

One randomized trial has tested an actual fish meal in pregnancy. In Norway, 133 pregnant women were assigned 14 oz (400 g) of cod a week for 16 weeks or their usual diet. Overall infant development scores did not differ (P = 0.633). In a secondary analysis, socio-emotional problem scores were lower in the cod group, 20.9 and 20.5 against 26.1 and 26.8 at 3 and 6 months. Cod is a lean, low-mercury fish, which is not the same as albacore or bigeye.

Omega-3, fish and mercury in pregnancy, on a risk scale
0.50.60.81.01.1no effectPreterm birth before 37 weeksCochrane, 26 RCTs, 10,304 womenPreterm birth before 37 weeks: 0.89 (95% CI 0.81 to 0.97)0.89Early preterm birth before 34 weeksCochrane, 9 RCTs, 5204 womenEarly preterm birth before 34 weeks: 0.58 (95% CI 0.44 to 0.77)0.58Low birthweightCochrane, omega-3 trialsLow birthweight: 0.90 (95% CI 0.82 to 0.99)0.90Autism diagnosis, any fish vs none32 US cohortsAutism diagnosis, any fish vs none: 0.84 (95% CI 0.77 to 0.92)0.84Problem-solving delay at age 391,909 Japanese pairs, top vs bottom fish fifthProblem-solving delay at age 3: 0.86 (95% CI 0.80 to 0.94)0.86Fine motor delay at age 3same cohortFine motor delay at age 3: 0.90 (95% CI 0.83 to 0.97)0.90Weaker gross motor score, per unit cord mercury882 Mediterranean childrenWeaker gross motor score, per unit cord mercury: 1.03 (95% CI 1.00 to 1.07)1.03
Randomized trialsObservational data

Below 1 means fewer cases. The first three rows are randomized trials of omega-3 fats, mostly capsules. The rest are observational and report odds, which cannot show cause. None of the rows isolates tuna. Sources: cards ev-tnpr-01, 08, 09 and 11 below.

Beyond trials the evidence is observational, and there is a lot of it. A 2025 systematic review of 40 articles, almost all cohorts, linked more seafood in pregnancy with better social, emotional and behavioral development in children aged 0 to 18, with certainty rated very low to moderate because randomized trials are missing. A review of 44 publications on 106,237 mother-child pairs linked seafood in pregnancy, from about 4 oz a week upward, with better child neurodevelopment, and found no net harm at the highest intakes despite more mercury. The authors could not judge individual species, tuna among them.

Two large cohorts point the same way. Across 32 US cohorts, any fish in pregnancy went with lower odds of an autism diagnosis than no fish, an odds ratio of 0.84 (0.77 to 0.92). In 91,909 Japanese mother-child pairs, the highest fish intake went with lower odds of delay in fine motor and problem-solving skills at age 3, odds ratios of 0.90 and 0.86. Neither study separated tuna, and people who eat fish differ from those who do not in other ways.

The tuna-specific data

Data on tuna alone come from one Spanish cohort, INMA, where fish intake is high. In 554 newborns from Valencia, mothers eating canned tuna twice a week or more had heavier babies than mothers eating it less than once a month (P for trend = 0.03), and a lower risk of a baby small for gestational age. The abstract does not give the size of that difference. In 1,644 mother-child pairs from the same cohort, high seafood intake in early pregnancy went with fewer attention errors at age 8, an incidence rate ratio of 0.76 (0.61 to 0.94), and the authors wrote that canned tuna showed weaker associations than other seafood.

Who should be careful

The risk with tuna is methylmercury, and it is measurable. In 1,883 Spanish mother-baby pairs, each doubling of canned tuna in pregnancy went with 8.4 percent more mercury in cord blood (95% CI 5.7 to 11.2), behind large oily fish at 11.4 percent and level with lean fish at 8.3 percent. That cohort comes from Spain, where people eat a lot of fish and many newborns were above the US EPA reference dose. In the Valencia cohort, babies in the top quarter of cord blood mercury weighed 5.1 oz (143.7 g) less than those in the bottom quarter (95% CI 35.6 to 251.8 g less), even as canned tuna itself went with heavier babies.

At low levels the harm is hard to find. In 1,308 mother-child pairs in Italy, Slovenia, Croatia and Greece, prenatal mercury showed no consistent harm to development at 18 months. The one signal was a borderline link between cord blood mercury and a weaker gross motor score, an odds ratio of 1.03 (1.00 to 1.07) in 882 children. The authors note that the nutrients in fish may mask harm from its mercury. In the Norwegian cod trial, 400 g a week raised hair mercury only slightly, a median of 554 against 485 mcg/kg (p = 0.186). Cod carries far less methylmercury than albacore or bigeye tuna, so that reassurance does not transfer to the high-mercury kinds.

Not for everyone. If you are pregnant or breastfeeding, the caution is about species and amount. Bigeye tuna is on the US list to avoid. Albacore and yellowfin count as Good Choices, a step below canned light tuna. The cards on this page say nothing about raw tuna in sushi, which raises a separate question of food safety.

What expert bodies say

The US FDA and EPA advise people who are pregnant or breastfeeding to eat between 8 and 12 oz a week of a variety of seafood from choices lower in mercury. Their chart places canned light tuna among the Best Choices and bigeye tuna among the choices to avoid. The European Food Safety Authority says 1 to 4 servings of fish a week bring health benefits, and that women of childbearing age should not exceed the tolerable weekly intake for methylmercury, to protect the fetus. The two bodies count in different units and agree on the direction.

How we searched

Searched: a local copy of the PubMed baseline, queried for tuna, fish or seafood with pregnancy and mercury or neurodevelopment (205 hits, top 40 screened), with preterm birth and birth weight (379 hits, top 25 screened), and for tuna on its own (35 hits, 30 screened). We added Europe PMC for three recent studies, a web search for the newest reviews and agency advice, the FDA and EFSA pages fetched twice each, and the ClinicalTrials.gov register. Search run on 6 October 2026.

Included: the Cochrane review of omega-3 in pregnancy, two systematic reviews of seafood and child development, the Norwegian cod trial in two reports, three reports from the Spanish INMA cohort, the US ECHO and Japanese JECS cohorts, the Mediterranean PHIME cohort on mercury, and the FDA/EPA and EFSA advice. None of the cited studies appears in Retraction Watch.

Excluded: a scoping review of how Spanish advice is implemented, which has no effect numbers. A Nordic scoping review with no numbers in its abstract. A 2015 review of 8 studies, superseded by the two newer ones. Risk models from 2005. Fish oil capsule trials, which the Cochrane review already covers. Surveys of metals and histamine in canned tuna, which sit on the canned tuna page.

What we read: abstracts from the PubMed baseline, full texts of the three Europe PMC studies, and the relevant sections of the FDA and EFSA pages.

What we could not get: the full EFSA 2014 scientific opinion. The EFSA news page printed the unit of the methylmercury weekly limit wrongly, so we did not use that number. We did not fetch the ACOG statement on fish in pregnancy.

What would change this answer

More on the fish itself: Tuna and Canned tuna.

The food behind this question

More questions about this food

The same question for other foods (pregnancy)

Sources

  1. ev-tnpr-01 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of RCTs with GRADE · n = 19,927
    Preterm birth < 37 weeks (13.4% versus 11.9%; risk ratio (RR) 0.89, 95% confidence interval (CI) 0.81 to 0.97; 26 RCTs, 10,304 participants; high-quality evidence) and early preterm birth < 34 weeks (4.6% versus 2.7%; RR 0.58, 95% CI 0.44 to 0.77; 9 RCTs, 5204 participants; high-quality evidence) were both lower in women who received omega-3 LCPUFA compared with no omega-3.
    Who: women at low, mixed or high risk of poor pregnancy outcomes; omega-3 LCPUFA supplements or food vs placebo or no omega-3
    Effect: preterm birth <37 wk RR 0.89 (95% CI 0.81 to 0.97; 26 RCTs, 10,304 participants; high quality); early preterm <34 wk RR 0.58 (0.44 to 0.77); low birthweight RR 0.90 (0.82 to 0.99)
    Certainty: Mostly capsule trials; tuna itself not tested. Child cognition and IQ showed very few differences (low to very low quality).
    Cochrane Database Syst Rev, 2018 · checked 2026-10-06 · we read the abstract
  2. ev-tnpr-02 · Observational data · systematic review of cohorts and one RCT, narrative synthesis with GRADE · n = 40 articles
    Evidence suggested relationships between higher seafood consumption and better social-emotional and behavioral development in children and adolescents aged 0-18 y as well as better aggregate scores of development for those <4 y. The certainty of the evidence was very low to moderate due to the lack of RCTs.
    Who: pregnant women and their children aged 0 to 18 years; 1 RCT, 24 prospective and 1 retrospective cohort
    Effect: better social-emotional, behavioral and aggregate development scores; overall cognition inconsistent; no studies on lactation; GRADE very low to moderate
    Certainty: Observational synthesis, so C. Canned tuna analyzed only as one fish type within cohorts.
    Adv Nutr, 2025 · checked 2026-10-06 · we read the abstract
  3. ev-tnpr-03 · Observational data · systematic review of observational studies (Dietary Guidelines methodology) · n = 106,237 mother-offspring pairs
    No net adverse neurocognitive outcomes were reported among offspring at the highest ranges of seafood intakes despite associated increases in mercury exposures.
    Who: healthy pregnant women and offspring in 44 publications
    Effect: benefits from about 4 oz/wk up to above 12 oz/wk; no net adverse neurocognitive outcomes at highest intakes despite more mercury; data insufficient by species mercury content
    Certainty: Observational; species-level conclusions (tuna) not possible per authors.
    Prostaglandins Leukot Essent Fatty Acids, 2019 · checked 2026-10-06 · we read the abstract
  4. ev-tnpr-04 · Randomized controlled trial(s) · randomized controlled trial, secondary analysis · n = 133
    We found no difference between infants in the intervention and control groups on total ASQ-2 scores (P = 0.633), but a difference on the ASQ:SE scores in favor of the intervention group (20.9 and 20.5 in the intervention group and 26.1 and 26.8 in the control group for 3 and 6 mo, respectively; P = 0.020).
    Who: pregnant women at or before 19 weeks in Norway, 200 g cod fillet twice weekly vs habitual diet for 16 weeks
    Effect: ASQ-2 total no difference (P = 0.633); ASQ:SE 20.9 and 20.5 vs 26.1 and 26.8 at 3 and 6 months (P = 0.020)
    Certainty: Lean low-mercury fish, not tuna; secondary outcome; small sample. NCT02610959.
    J Nutr, 2021 · checked 2026-10-06 · we read the abstract
  5. ev-tnpr-05 · Randomized controlled trial(s) · randomized controlled trial · n = 137
    Post-intervention, the intervention group had median (inter-quartile range) THHg concentrations of 554 (392-805) µg/kg, and the control group 485 (341-740) µg/kg (p = 0.186).
    Who: pregnant women in Norway, gestational week 20 to 36, 400 g cod fillets per week vs habitual diet
    Effect: post-intervention hair mercury median 554 vs 485 ug/kg (p = 0.186); 8% above US EPA hair reference 1,000 ug/kg (6 intervention, 4 control)
    Certainty: Cod has far less methylmercury than albacore or bigeye tuna; result does not transfer to high-mercury tuna.
    Environ Int, 2020 · checked 2026-10-06 · we read the abstract
  6. ev-tnpr-06 · Observational data · population-based birth cohort · n = 1,883
    A doubling in consumption of large oily fish was associated with an increase of 11.4% (95%CI: 3.8 to 19.6%) in cord blood T-Hg levels, followed by an increase of 8.4% (95%CI: 5.7 to 11.2%) in the case of canned tuna and 8.3% (95%CI: 5.5 to 11.1%) in that of lean fish.
    Who: mother-child pairs in the Spanish INMA cohort, 2004 to 2008
    Effect: cord blood total mercury +8.4% (95% CI 5.7 to 11.2) per doubling of canned tuna; +11.4% (3.8 to 19.6) large oily fish; +8.3% lean fish; geometric mean 8.2 ug/L
    Certainty: Spain has high fish intake (78 g/day); many newborns above US EPA reference dose.
    Environ Int, 2011 · checked 2026-10-06 · we read the abstract
  7. ev-tnpr-07 · Observational data · prospective mother-infant cohort · n = 554
    Mothers consuming >/=2 portions/wk of canned tuna had newborns who weighed more than those who consumed <1 portion/mo (P for trend = 0.03) and a lower risk of having infants who were SGA for weight (P for trend = 0.01).
    Who: newborns in a population-based Valencia cohort, 2004 to 2006, with cord blood mercury
    Effect: top vs bottom mercury quartile: birth weight -143.7 g (95% CI -251.8 to -35.6); canned tuna >=2 portions/wk vs <1/month: higher birth weight (P for trend = 0.03), lower SGA risk (P for trend = 0.01)
    Certainty: Size of the tuna effect not given in the abstract; single region.
    Am J Clin Nutr, 2009 · checked 2026-10-06 · we read the abstract
  8. ev-tnpr-08 · Observational data · cohort consortium analysis · n = 3,939
    In adjusted regression models, relative to no fish intake, fish intake during pregnancy was associated with reduced odds of autism diagnosis (odds ratio: 0.84; 95% confidence interval [CI]: 0.77, 0.92), and a modest reduction in raw total SRS scores (β: -1.69; 95% CI: -3.3, -0.08).
    Who: children born 1999 to 2019 in 32 ECHO cohorts, maternal self-reported fish intake in pregnancy
    Effect: autism diagnosis OR 0.84 (95% CI 0.77 to 0.92); SRS total score beta -1.69 (-3.3 to -0.08); similar from under once a week to more than twice a week
    Certainty: Self-reported fish, all species pooled; OR, not risk.
    Am J Clin Nutr, 2024 · checked 2026-10-06 · we read the abstract
  9. ev-tnpr-09 · Observational data · nationwide prospective birth cohort · n = 91,909
    Consistently lower odds were found for the highest vs. lowest quintile for the domains of communication, fine motor, problem-solving, and personal-social but not gross motor skills, with adjusted odd ratios (95% confidence intervals) of 0.89 (0.80-0.998), 0.90 (0.83-0.97), 0.86 (0.80-0.94), 0.87 (0.77-0.98), and 1.04 (0.94-1.16), respectively.
    Who: mother-child pairs in the Japan Environment and Children's Study, ASQ-3 at age 3
    Effect: highest vs lowest quintile aOR: fine motor 0.90 (0.83 to 0.97), problem-solving 0.86 (0.80 to 0.94), personal-social 0.87 (0.77 to 0.98), communication 0.89 (0.80 to 0.998); gross motor 1.04 (0.94 to 1.16)
    Certainty: Japanese diets are fish-rich; tuna not separated.
    Front Public Health, 2023 · checked 2026-10-06 · we read the abstract
  10. ev-tnpr-10 · Observational data · prospective birth cohort · n = 1,644
    Shellfish and canned tuna showed weaker associations.
    Who: mother-child pairs in the INMA cohort, Spain, recruited 2003 to 2008
    Effect: ANT omission errors IRR 0.76 (95% CI 0.61 to 0.94), top (854 g/wk) vs bottom (195 g/wk) quintile; shellfish and canned tuna weaker
    Certainty: Size for canned tuna alone not given in the abstract.
    Int J Epidemiol, 2020 · checked 2026-10-06 · we read the abstract
  11. ev-tnpr-11 · Observational data · meta-analysis of four national birth sub-cohorts · n = 1,308
    The meta-analysis of logistic regression models showed that the overall adjusted OR between THg in cord blood and suboptimal gross motor score was borderline significant (n = 882; OR = 1.03; 95%CI: 1.00-1.07).
    Who: mother-child pairs in the PHIME cohort (Italy, Slovenia, Croatia, Greece), Bayley-III at 18 months
    Effect: cord blood mercury and suboptimal gross motor OR 1.03 (95% CI 1.00 to 1.07, n = 882); maternal hair mercury positively linked to language score (beta 0.55, 0.05 to 1.05)
    Certainty: Fish intake confounds mercury (fish nutrients may mask harm); not about tuna directly.
    Int J Hyg Environ Health, 2019 · checked 2026-10-06 · we read the abstract
  12. ev-tnpr-12 · Position of an expert body · agency consumer advice · n = —
    Those who are pregnant or breastfeeding consume between 8 and 12 ounces per week of a variety of seafood from choices that are lower in mercury.
    Who: people who are pregnant or breastfeeding
    Effect: 8 to 12 oz/week (1 serving = 4 oz); canned light (incl. skipjack) Best Choice; albacore and yellowfin Good Choice; bigeye Choice to Avoid, highest mercury
    Certainty: T2, level E. Chart labels confirmed on the same page; NHS (UK) instead caps tuna at 4 medium cans a week, not in trust.json.
    US FDA/EPA, Advice about Eating Fish (page updated 03/05/2024) · checked 2026-10-06 · we read the section
  13. ev-tnpr-13 · Position of an expert body · agency scientific statement (news summary of EFSA opinions 2014-2015) · n = —
    To protect the foetus against the adverse neurodevelopmental effects of methylmercury, women of childbearing age should not exceed the TWI.
    Who: women of childbearing age, pregnant women, children
    Effect: 1-2 to 3-4 fish servings/week for benefits; methylmercury TWI not to be exceeded; high-mercury species limited
    Certainty: T2, level E. Disagrees in form with FDA/EPA (servings vs ounces) but agrees on direction.
    EFSA, Fish: scenarios indicate benefits versus risks (news, 22 January 2015) · checked 2026-10-06 · we read the section

How this page was made. Evidence was extracted from primary sources into cards, every number was re-checked against the source, and the text was written from those cards. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.

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