Mayo Clinic Health Manager

Get free personalized health guidance for you and your family.

Get Started

Free

E-Newsletter

Subscribe to receive the latest updates on health topics. About our newsletters

  • Housecall
  • Alzheimer's caregiving
  • Living with cancer

Pregnancy and fish: What's too little — or too much?

If you're confused about whether it's safe to eat seafood during your pregnancy, you're not alone. Understand the guidelines for pregnancy and fish.

By Mayo Clinic staff

Photo of Roger Harms, M.D.
Roger Harms, M.D.

If you're pregnant, you may feel like you need to become a nutrition expert overnight. After all, what you eat and drink — and what you avoid — influences your baby's development. Some choices are logical, such as eating plenty of fruits and vegetables and eliminating alcohol from your diet. But what about seafood? When it comes to pregnancy and fish, researchers give mixed reports.

Here, Roger Harms, M.D., a pregnancy specialist at Mayo Clinic, Rochester, Minn., and medical editor-in-chief of MayoClinic.com, offers practical advice about pregnancy and fish.

What's the link between pregnancy and fish?

Seafood can be a great source of protein and iron — crucial nutrients for your baby's growth and development. And the omega-3 fatty acids in many fish can promote your baby's brain development. Research has shown that skimping on seafood during pregnancy may contribute to a child having poor verbal skills, behavioral problems and other early developmental issues.

But some types of seafood — particularly large, predatory fish such as shark, swordfish, king mackerel and tilefish — may contain high levels of mercury. Although the mercury in seafood isn't a concern for most adults, special precautions apply if you're pregnant or planning to become pregnant. If you regularly eat fish high in mercury, the substance can accumulate in your bloodstream over time. In turn, too much mercury in your bloodstream may damage your baby's developing brain and nervous system.

What's safe to eat?

Some types of seafood contain little mercury. The Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) say pregnant women can safely eat up to 12 ounces a week (340 grams) or two average meals of:

  • Shrimp
  • Canned light tuna (limit albacore tuna and tuna steak to no more than 6 ounces a week)
  • Salmon
  • Pollock
  • Catfish

But some research suggests that limiting seafood during pregnancy may do more harm than good, since the risks from losing important nutrients may exceed the risks of harm due to mercury exposure. A 2007 British study found that women who ate 12 ounces (340 grams) or less of seafood a week were more likely to have children with verbal or other communication problems at age 3, and behavioral problems and trouble with fine motor skills by ages 7 and 8. No negative effects were noted for women who ate more seafood than the FDA-approved guidelines.

Next page
(1 of 2)
References
  1. Position of the American Dietetic Association: Nutrition and lifestyle for a healthy pregnancy outcome. Journal of the American Dietetic Association. 2008;108:553.
  2. Makrides M. Outcomes for mothers and their babies: Do n-3 long-chain polyunsaturated fatty acids and seafoods make a difference? Journal of the American Dietetic Association. 2008;108:1622.
  3. Oken E, et al. Associations of maternal fish intake during pregnancy and breastfeeding duration with attainment of developmental milestones in early childhood: A study from the Danish national birth cohort. American Journal of Clinical Nutrition. 2008;88:789.
  4. What you need to know about mercury in fish and shellfish. U.S. Environmental Protection Agency. http://www.epa.gov/waterscience/fish/advice/. Accessed Jan. 8, 2009.
  5. Nutrition during pregnancy. The American College of Obstetricians and Gynecologists. http://www.acog.org/publications/patient_education/bp001.cfm. Accessed Jan. 8, 2009.
  6. Hibbeln JR, et al. Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): An observational cohort study. The Lancet. 2007;369:578.
  7. Dunstan JA, et al. Cognitive assessment of children at age 2 1/2 years after maternal fish oil supplementation in pregnancy: A randomized controlled trial. Archives of Childhood Diseases: Fetal and Neonatal Edition. 2008;93:F45.
  8. Fish facts: Print-and-go guide. National Women's Health Information Center. http://www.womenshealth.gov/pregnancy/tools/preg_fish.pdf. Accessed Jan. 8, 2009.
  9. Fresh and frozen seafood: Selecting and serving it safely. U.S. Food and Drug Administration. http://www.cfsan.fda.gov/~acrobat/seafsafe.pdf. Accessed Jan. 8, 2009.
  10. Foran SE, et al. Measurement of mercury levels in concentrated over-the-counter fish oil preparations: Is fish oil healthier than fish? Archives of Pathology & Laboratory Medicine. 2003;127:1603.

PR00158

March 20, 2009

© 1998-2009 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "EmbodyHealth," "Reliable tools for healthier lives," "Enhance your life," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research.

Print Share Reprints

Text Size: smaller largerlarger