Are mussels safe during pregnancy?

Cooked mussels fit within the seafood advice for pregnancy, and raw or undercooked mussels do not. No randomized trial or cohort has studied mussels on their own in pregnant women, so the answer is assembled from nearby evidence. The strongest piece is about omega-3 fats, which mussels contain. A Cochrane review of 70 randomized trials in 19,927 women found omega-3 lowered preterm birth before 37 weeks from 13.4 to 11.9 percent (RR 0.89, 95% CI 0.81 to 0.97), mostly with fish oil capsules and never with mussels. The US FDA and EPA count shellfish as fish and advise people who are or may become pregnant to eat 2 to 3 servings a week from their Best Choices list. Mussels are not named on that list.

Established. Omega-3 fats taken in pregnancy lower the risk of an early birth. In the Cochrane review, birth before 34 weeks fell from 4.6 to 2.7 percent (RR 0.58, 95% CI 0.44 to 0.77, 9 trials, 5204 women), on high-quality evidence. That finding is about omega-3, mostly from capsules, and nobody has tested it with mussels.

Not for everyone. Raw and undercooked shellfish are on the FDA list of foods for pregnant women to avoid. The FDA advises cooking mussels until the shells open.

What the trials found

Omega-3 in pregnancy

Two large syntheses of randomized trials point the same way. Besides the Cochrane result above, a meta-analysis of 59 trials of DHA, EPA or ALA taken at least twice a week found preeclampsia was 16 percent less likely (RR 0.84, 95% CI 0.74 to 0.96, 21,919 women), and preterm birth before 37 weeks 14 percent less likely (RR 0.86, 95% CI 0.77 to 0.95, 15,510 women). These were supplement trials, and some outcomes varied a lot between them.

How much omega-3 a mussel meal brings is a separate question. In one controlled feeding trial, blue mussels eaten at five meals a week gave 0.18 g of EPA and 0.16 g of DHA a day, averaged over the week. The authors note that this varies with water, season and feed, so treat it as one worked example.

Shellfish and seafood in observational studies

The only review aimed at shellfish is a 2025 scoping review of 46 studies on molluscs and crustaceans from pregnancy to age two. It found no link between shellfish and preterm birth. Birth weight results were mixed, and several studies reported lower birth weight with higher shellfish intake. The review did not pool its studies, and most of them were observational.

Single studies that separated shellfish give a mixed picture. In 3279 pregnant women in Washington State, shellfish eaten around conception was not linked to gestational hypertension, preeclampsia, gestational diabetes or preterm birth, but the median intake was only 0.3 servings a week. In a Spanish case-control study of 518 pairs, women eating shellfish more than once a week had lower odds of a baby small for gestational age (OR 0.25, 95% CI 0.08 to 0.76). Diet there was recalled after the birth, and the interval is wide. In 10,179 women interviewed after delivery in Gansu, China, fish and shellfish together were linked to lower odds of preterm birth (OR 0.65, 95% CI 0.56 to 0.77).

Fish in general has the largest data set. Pooled data from 19 European birth cohorts, 151,880 mothers and children, linked eating fish more than once but under three times a week with a 13 percent lower risk of preterm birth (RR 0.87, 95% CI 0.82 to 0.92) and birth weight higher by 8.9 g. Shellfish was not separated from fish there.

Unsettled. Whether mussels themselves improve birth outcomes is unknown. The omega-3 trials used capsules, the cohorts mostly lumped shellfish with fish, and the one review of shellfish found no preterm link and birth weight results that point both ways.

Who should be careful

Every pregnant woman, when it comes to raw shellfish. A systematic review of 359 shellfish-borne viral outbreaks from 1980 to 2012 found norovirus in 84 percent and hepatitis A in 13 percent, often from sewage-contaminated water or undercooking. Oysters made up 58.4 percent of the implicated shellfish, and the review did not look at pregnancy. Mussels and other bivalves concentrate norovirus as they filter water, and a narrative review found high viral loads survive both depuration and ordinary food preparation. It does not say which cooking time or temperature is enough. In Tasmania, Vibrio parahaemolyticus turned up in every one of eleven commercial shellfish growing areas in summer and autumn, in 8 to 100 percent of samples, which describes raw shellfish at harvest rather than what reaches a plate after chilling and cooking.

Not for everyone. Cooking does not destroy the algal toxins that mussels can carry. In the 1987 Prince Edward Island outbreak, 107 people fell ill after eating cultivated mussels contaminated with domoic acid, 19 were hospitalized and 3 died. That was a single outbreak, and harvest waters are now monitored. We found no data on these toxins in pregnant women.

Shellfish also bring contaminants. The scoping review found shellfish eaters in pregnancy and early childhood had higher biomarkers of environmental contaminants, with mercury the best studied. These were blood and hair measures, without clinical outcomes. In a randomized trial of 102 Norwegian adults aged 48 to 76, eating 2.2 lb (1 kg) of fish and mussels a week for 26 weeks raised blood mercury by 5.1 ng/ml (95% CI 4.4 to 5.8), arsenic by 7.1 ng/ml (95% CI 5.0 to 9.2) and lead by 2.6 ng/ml (95% CI 0.0 to 5.2) against controls. Those people were not pregnant, ate far more than usual, and the trial cannot split the metals between fish and mussels.

The omega-3 trials also found a cost. Pregnancies running past 42 weeks probably rose from 1.6 to 2.6 percent with omega-3 (RR 1.61, 95% CI 1.11 to 2.33, 6 trials, 5141 women), on moderate-quality evidence from supplement doses, which are larger than mussels supply.

A rare reaction to keep in mind: two adult women had repeated bouts of severe vomiting and diarrhea a few hours after eating mussels, with normal allergy tests, and were diagnosed with food protein-induced enterocolitis syndrome. Two cases say nothing about how common it is. We have no cards on shellfish allergy in pregnancy.

What expert bodies say

The US FDA tells pregnant women, young children, older adults and people with weakened immune systems to avoid raw or undercooked fish or shellfish, including sashimi, some sushi and ceviche. In the same advice it says to cook mussels, clams and oysters until the shells open and to throw out any that stay closed. The FDA and EPA joint advice on eating fish treats fish and shellfish together and recommends 2 to 3 servings of 4 oz a week from Best Choices for people who are or may become pregnant or are breastfeeding. Mussels are absent from that chart, while clams, oysters and scallops are listed as Best Choices, and we found no FDA mercury value for mussels.

How we searched

What would change this answer

• A prospective cohort that separates mussels and other bivalves from the rest of seafood and records both birth outcomes and maternal mercury and cadmium. None is registered.
• Any data on algal toxins such as domoic acid in pregnant women.
• A published FDA mercury value for mussels, which would place them on the Best Choices chart or off it.

Nutrition facts and more on mussels themselves are on the mussels page.

Sources

1. ev-muspg-01 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 19,927 women in 70 RCTs
   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: pregnant women at low, mixed or high risk; omega-3 LCPUFA supplements or food vs placebo or no omega-3
   Effect: preterm <37 wk RR 0.89 (95% CI 0.81 to 0.97; 26 RCTs, 10,304); early preterm <34 wk RR 0.58 (0.44 to 0.77; 9 RCTs, 5204); high-quality evidence
   Certainty: Mostly fish oil capsules; mussels supply EPA and DHA but no trial used mussels.
   Cochrane Database Syst Rev, 2018 · checked 2026-10-07 · we read the abstract
2. ev-muspg-02 · Meta-analysis or systematic review · Cochrane systematic review and meta-analysis of randomized controlled trials · n = 5141 in 6 RCTs
   Prolonged gestation > 42 weeks was probably increased from 1.6% to 2.6% in women who received omega-3 LCPUFA compared with no omega-3 (RR 1.61 95% CI 1.11 to 2.33; 5141 participants; 6 RCTs; moderate-quality evidence).
   
   Who: pregnant women in RCTs of omega-3 LCPUFA vs no omega-3
   Effect: prolonged gestation >42 wk RR 1.61 (95% CI 1.11 to 2.33); moderate-quality evidence
   Certainty: Supplement trials; a food source like mussels gives smaller doses.
   Cochrane Database Syst Rev, 2018 · checked 2026-10-07 · we read the abstract
3. ev-muspg-03 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 59 RCTs
   RESULTS: In 24 comparisons (21,919 women) n-3 fatty acids played a protective role against the risk of preeclampsia (RR = 0.84, 95% CI 0.74-0.96 p = 0.008; I2 = 24%).
   
   Who: pregnant women, oral DHA, EPA or ALA at least twice a week vs no supplement or placebo
   Effect: preeclampsia RR 0.84 (95% CI 0.74 to 0.96; 24 comparisons, 21,919 women); preterm <37 wk RR 0.86 (0.77 to 0.95; 15,510 women)
   Certainty: Supplements, not mussels; heterogeneity high for some outcomes.
   Arch Gynecol Obstet, 2023 · checked 2026-10-07 · we read the abstract
4. ev-muspg-04 · Observational data · scoping review (PROSPERO CRD42022320454) · n = 46 articles
   Preterm birth was not associated with shellfish consumption, but newborn anthropometry showed mixed results, with several studies reporting lower birth weight with higher shellfish consumption.
   
   Who: pregnant and lactating women and children 0 to 2 years eating shellfish, studies 2000 to 2022
   Effect: preterm birth not associated; several studies lower birth weight with higher shellfish intake; higher mercury biomarkers; better iodine status
   Certainty: Scoping review without pooling; mostly observational studies.
   Nutr Res Rev, 2025 · checked 2026-10-07 · we read the abstract
5. ev-muspg-05 · Observational data · scoping review · n = 46 articles
   Overall, shellfish consumption was associated with higher biomarkers of environmental contaminants, with mercury being the most studied and having the strongest evidence base.
   
   Who: pregnant and lactating women and children 0 to 2 years eating shellfish
   Effect: higher biomarkers of environmental contaminants; mercury strongest evidence base
   Certainty: Biomarkers, not clinical outcomes.
   Nutr Res Rev, 2025 · checked 2026-10-07 · we read the abstract
6. ev-muspg-06 · Observational data · meta-analysis of pooled birth cohort data · n = 151,880
   RESULTS: Women who ate fish >1 time/wk during pregnancy had lower risk of preterm birth than did women who rarely ate fish (≤ 1 time/wk); the adjusted RR of fish intake >1 but <3 times/wk was 0.87 (95% CI: 0.82, 0.92), and for intake ≥ 3 times/wk, the adjusted RR was 0.89 (95% CI: 0.84, 0.96).
   
   Who: mother-child pairs from 19 population-based European birth cohorts
   Effect: preterm birth RR 0.87 (95% CI 0.82 to 0.92) for >1 to <3 times/week; RR 0.89 (0.84 to 0.96) for 3 or more; birth weight +8.9 g and +15.2 g
   Certainty: Observational; fish in general, shellfish not separated.
   Am J Clin Nutr, 2014 · checked 2026-10-07 · we read the abstract
7. ev-muspg-07 · Observational data · prospective cohort · n = 3279
   CONCLUSIONS: Higher intake of lean fish, but not fatty fish or shellfish, was associated with a higher risk of preterm birth; these findings may have significance for preterm birth prevention.
   
   Who: women recruited from prenatal clinics, Washington State, 1996 to 2008 (Omega study); median shellfish 0.3 servings/week
   Effect: shellfish and total seafood not associated with complications; lean fish >1 serving/week preterm RR 1.55 (95% CI 1.04 to 2.30)
   Certainty: Low shellfish intake in this cohort; FFQ exposure.
   Public Health Nutr, 2016 · checked 2026-10-07 · we read the abstract
8. ev-muspg-08 · Observational data · matched case-control study · n = 518 pairs
   RESULTS: Shellfish intake more than once/week yielded a significant protective effect against an SGA newborn (OR 0.25, 95% CI 0.08 to 0.76, after adjusting for energy, educational level, smoking, prepregnancy body mass index, weight and a history of preterm or low birthweight newborn).
   
   Who: pregnant Spanish women, 5 hospitals in Eastern Andalusia, SGA cases and matched controls
   Effect: shellfish >1/week adjusted OR 0.25 (95% CI 0.08 to 0.76) for SGA
   Certainty: Recall of diet after birth; wide interval.
   BMJ Open, 2018 · checked 2026-10-07 · we read the abstract
9. ev-muspg-09 · Observational data · retrospective study with FFQ after delivery · n = 10,179
   Fish and shellfish consumption was associated with reduced risk of preterm birth (OR = 0·65, 95 % CI 0·56, 0·77).
   
   Who: women interviewed after delivery, Gansu province, China
   Effect: preterm birth OR 0.65 (95% CI 0.56 to 0.77), trend with frequency and amount
   Certainty: Retrospective recall; fish and shellfish combined.
   Br J Nutr, 2022 · checked 2026-10-07 · we read the abstract
10. ev-muspg-10 · Randomized controlled trial(s) · randomized controlled trial, 26 weeks · n = 102
    The difference in mean change for intervention compared with control persons was 5.1 ng ml(-1) (95% confidence interval (CI) = 4.4, 5.8) for mercury, 7.1 ng ml(-1) (95% CI = 5.0, 9.2) for arsenic, and 2.6 ng ml(-1) (95% CI = 0.0, 5.2) for lead.
    
    Who: healthy non-smoking men and women aged 48 to 76, Norway; intervention 2.2 lb (1 kg) fish and mussels per week vs usual diet
    Effect: mercury +5.1 ng/ml (95% CI 4.4 to 5.8), arsenic +7.1 (5.0 to 9.2), lead +2.6 (0.0 to 5.2)
    Certainty: Not pregnant women; intake far above usual; fish and mussels together.
    Food Addit Contam Part A Chem Anal Control Expo Risk Assess, 2015 · checked 2026-10-07 · we read the abstract
11. ev-muspg-11 · Observational data · systematic review of outbreak reports · n = 359 outbreaks
    The most common viral pathogens involved were norovirus (83.7 %) and hepatitis A virus (12.8 %).
    
    Who: reported shellfish-borne viral outbreaks worldwide, 1980 to 2012
    Effect: norovirus 83.7%, hepatitis A 12.8%; oysters 58.4% of implicated shellfish
    Certainty: Outbreak reports; not pregnancy-specific.
    Food Environ Virol, 2013 · checked 2026-10-07 · we read the abstract
12. ev-muspg-12 · Observational data · case series (outbreak investigation) · n = 107
    From the more than 250 reports received, 107 patients met the case definition.
    
    Who: people in Canada who ate mussels from three Prince Edward Island estuaries, 1987
    Effect: vomiting 76%, memory loss 25%, 19 hospitalized, 12 intensive care, 3 deaths
    Certainty: Single outbreak; harvest monitoring now in place; cooking does not destroy algal toxins.
    N Engl J Med, 1990 · checked 2026-10-07 · we read the abstract
13. ev-muspg-13 · Position of an expert body · agency consumer advice · n = —
    Raw or undercooked fish or shellfish, or food containing raw or undercooked seafood (for example, sashimi) found in some sushi or ceviche.
    
    Who: pregnant women, children, older adults, people with weakened immune systems
    Effect: avoid raw or undercooked fish or shellfish, sushi, sashimi, ceviche
    Certainty: General seafood advice; mussels named in the cooking section of the same page.
    US FDA, Selecting and Serving Fresh and Frozen Seafood Safely · checked 2026-10-07 · we read the section
14. ev-muspg-14 · Position of an expert body · agency consumer advice · n = —
    The shells open during cooking
    
    Who: all consumers
    Effect: cook until shells open; discard unopened; most seafood to 145 F
    Certainty: Kitchen practice advice; does not inactivate algal toxins.
    US FDA, Selecting and Serving Fresh and Frozen Seafood Safely · checked 2026-10-07 · we read the section
15. ev-muspg-15 · Position of an expert body · agency consumer advice · n = —
    This advice refers to fish and shellfish collectively as
    
    Who: people who might become or are pregnant or breastfeeding, children 1 to 11
    Effect: 2 to 3 servings of 4 oz a week from Best Choices; mussels are not named on the chart
    Certainty: Mussels absent from the FDA chart; other bivalves (clam, oyster, scallop) are Best Choices.
    US FDA and EPA, Advice about Eating Fish · checked 2026-10-07 · we read the section
16. musl-r5-07 · Observational data · case series · n = 2
    In this case report, we describe two adult women with recurrent episodes of severe vomiting and diarrhoea within a few hours of intake of mussels.
    
    Who: two adult women with recurrent reactions to mussels and negative allergy testing
    Effect: severe vomiting and diarrhea within a few hours of intake, recurring with each exposure
    Certainty: Two cases cannot say how common this is; the point is that the reaction is not IgE-mediated, so standard allergy testing comes back normal and the cause is missed.
    Ugeskr Laeger, 2025 · checked 2026-09-24 · we read the abstract
17. musl-r5-08 · Observational data · review of outbreak and prevalence studies · n = two decades of outbreak and prevalence reports
    The authors describe how their physiology of filter feeding can render them concentrated vehicles of norovirus contamination in polluted environments and how high viral loads persist in molluscs even after application of depuration practices and typical food preparation steps.
    
    Who: bivalve molluscs implicated in gastroenteritis outbreaks over two decades of published reports
    Effect: viral load persists after depuration and typical food preparation; no effect size is given
    Certainty: A narrative review rather than a pooled analysis, and it does not say which cooking temperature or time would be enough.
    Transbound Emerg Dis, 2020 · checked 2026-09-24 · we read the abstract
18. musl-r5-09 · Randomized controlled trial(s) · randomized single-blinded crossover feeding trial · n = 23 completed
    The blue mussels consumed every week provided 0.24 g saturated fat, 0.14 g monounsaturated fat, 0.47 g polyunsaturated fat, 0.18 g EPA, and 0.16 g DHA daily.
    
    Who: women with rheumatoid arthritis during the blue mussel period of a crossover feeding trial, five meals a week for 11 weeks
    Effect: 0.18 g EPA and 0.16 g DHA daily, against 0.00 g EPA and 0.01 g DHA in the meat period
    Certainty: One feeding schedule in one trial, and the figure is a weekly intake spread over seven days rather than the content of a single portion; the omega-3 content of mussels varies with water, season and feed, so this is a worked example rather than a constant.
    Molecules, 2023 · checked 2026-09-24 · we read the section
19. musl-r5-12 · Observational data · multi-seasonal prevalence survey · n = 11 growing areas
    Vibrio parahaemolyticus was detected in all surveyed growing areas during the three summer/autumn sampling periods, with a prevalence of 8-100 %.
    
    Who: eleven commercial oyster and mussel growing areas in Tasmania sampled at harvest between 2020 and 2022
    Effect: prevalence 8-100 percent in summer and autumn, 17-33 percent in the five areas where it was found in winter and spring; levels usually below 10 MPN/g
    Certainty: Prevalence at harvest in one region of Australia; it describes the raw material, not what reaches a plate after chilling and cooking.
    Int J Food Microbiol, 2025 · checked 2026-09-24 · we read the abstract