Can I Have Tuna While Pregnant? Safety Guidelines and Mercury Risks

Pregnancy brings many dietary questions, and one of the most common concerns expecting mothers have is whether they can safely eat tuna. The answer is yes, but with important qualifications regarding the type of tuna and quantity consumed.

Tuna offers valuable nutrients that support fetal development, yet it also contains mercury that can potentially harm your growing baby. Understanding which types of tuna are safest and how much you can eat will help you make informed choices throughout your pregnancy.

Nutritional Benefits of Tuna During Pregnancy

Tuna provides several essential nutrients that play critical roles in your baby’s development and your overall health during pregnancy:

High-Quality Protein

Protein is fundamental for your baby’s growth and tissue development. A 3.5-ounce serving of canned light tuna delivers approximately 32% of your daily protein needs. Adequate protein intake supports proper fetal development and helps prevent complications like low birth weight.

Omega-3 Fatty Acids (EPA and DHA)

Tuna is one of the richest dietary sources of long-chain omega-3 fatty acids, particularly EPA and DHA. These essential fats are crucial for:

• Brain development and cognitive function
• Eye and vision development
• Nervous system formation
• Reducing risk of preterm birth
• Supporting healthy birth weight
• Potentially lowering maternal depression risk

A standard portion of light canned tuna contains approximately 25 mg of EPA and 197 mg of DHA, which represents 63-100% of the daily amount experts recommend for pregnant women.

Vitamin D

Tuna contains vitamin D, which is essential for bone health and immune function. Adequate vitamin D levels during pregnancy may help reduce the risk of miscarriage and preeclampsia, a serious pregnancy complication characterized by high blood pressure.

Vitamin B12

One serving of canned light tuna provides over 100% of your daily vitamin B12 needs. This vitamin is vital for nervous system function and the production of red blood cells. Low B12 levels during pregnancy have been linked to increased risks of miscarriage, preterm birth, and birth defects.

Iron

Iron supports your baby’s brain and nervous system development. Tuna provides about 9% of your daily iron needs per serving. Adequate iron intake helps prevent low birth weight, preterm delivery, and maternal complications.

Understanding Mercury Risks in Tuna

While tuna offers significant nutritional benefits, the primary concern for pregnant women is its mercury content. Mercury is a naturally occurring element, but industrial pollution has increased its concentration in ocean waters and fish.

How Mercury Affects Pregnancy

Mercury accumulates in fish tissues, particularly in larger, older predatory species like tuna. When consumed during pregnancy, high mercury levels can cross the placenta and potentially harm your baby’s developing brain and nervous system.

Excessive mercury exposure during pregnancy may result in:

• Delayed motor skill development
• Learning difficulties and cognitive impairment
• Speech and language delays
• Memory and attention problems
• Reduced visual-spatial abilities
• Lower IQ scores
• Increased risk of cardiovascular issues later in life

In severe cases, very high mercury exposure can cause vision or hearing loss, birth defects, seizures, or more serious complications. However, these extreme outcomes are rare with typical dietary tuna consumption.

Why Some Tuna Contains More Mercury

Not all tuna species contain equal amounts of mercury. Larger tuna species that live longer and occupy higher positions in the food chain accumulate more mercury throughout their lifetime. This is why certain types of tuna pose greater risks than others.

Safe Types and Amounts of Tuna During Pregnancy

The Food and Drug Administration (FDA) provides specific guidelines to help pregnant women enjoy tuna’s benefits while minimizing mercury exposure.

Recommended Amounts

Pregnant women should consume 8-12 ounces of fish and seafood per week, with no more than one of the following options:

Option 1: Up to 12 ounces (340 grams) per week of canned light tuna

Option 2: Up to 4 ounces (112 grams) per week of albacore (white) tuna or yellowfin tuna

This weekly limit ensures you receive nutritional benefits while keeping mercury exposure within safe levels.

Best Choices: Low Mercury Tuna

Canned Light Tuna: This is the safest choice for pregnant women. Light tuna typically comes from smaller species like skipjack, which accumulate less mercury. You can safely eat up to 12 ounces weekly.

Good Choices: Moderate Mercury Tuna

Albacore (White) Tuna: This variety contains moderate mercury levels. Limit consumption to 4 ounces per week.

Yellowfin Tuna: Similar to albacore, yellowfin should be limited to 4 ounces weekly.

Fish to Avoid: High Mercury Content

Pregnant women should completely avoid these high-mercury tuna and fish varieties:

• Bigeye tuna
• Swordfish
• Shark
• King mackerel
• Marlin
• Orange roughy
• Tilefish from the Gulf of Mexico

Important Preparation and Safety Guidelines

Always Choose Cooked Tuna

Raw or undercooked tuna poses risks beyond mercury content. Raw fish can harbor harmful bacteria like Listeria monocytogenes, which can cause listeriosis—a serious infection that can severely impact fetal development and potentially lead to miscarriage, stillbirth, or severe newborn illness.

Always eat fully cooked tuna during pregnancy. This includes:

• Canned tuna (which is fully cooked during processing)
• Baked or grilled tuna steaks cooked to an internal temperature of 145°F
• Tuna in casseroles or hot dishes

Avoid these raw or undercooked tuna preparations:

• Sushi or sashimi with raw tuna
• Tuna tartare
• Seared tuna that’s raw in the center
• Ceviche

Check Labels and Choose Quality Products

When purchasing canned tuna, read labels carefully to identify whether you’re buying light or albacore tuna. Look for products from reputable brands that follow safety standards.

Other Safe Fish Options During Pregnancy

If you want to diversify your seafood intake or prefer alternatives to tuna, many fish species are low in mercury and safe during pregnancy:

• Salmon (wild or farmed)
• Sardines
• Anchovies
• Herring
• Tilapia
• Cod
• Catfish
• Pollock
• Trout
• Shrimp

These fish provide similar nutritional benefits to tuna, including omega-3 fatty acids and protein, with lower mercury concerns.

What If You Don’t Eat Tuna or Fish?

If you avoid tuna due to allergies, dietary restrictions, ethical reasons, or personal preference, you can still obtain essential nutrients through other sources:

Alternative Omega-3 Sources

• Flaxseeds and flaxseed oil
• Chia seeds
• Walnuts
• Hemp seeds
• Eggs fortified with omega-3s
• Algae-based omega-3 supplements

Consider Supplementation

If you don’t consume fish regularly, discuss with your healthcare provider about taking a prenatal supplement containing at least 200 mg of DHA or 250 mg combined EPA and DHA daily. Many prenatal vitamins now include these omega-3 fatty acids, but some may require an additional supplement.

Protein Alternatives

Meet your protein needs through lean meats, poultry, eggs, dairy products, legumes, nuts, and seeds. A varied diet can provide all essential amino acids your baby needs.

Practical Tips for Eating Tuna During Pregnancy

Track Your Weekly Intake

Keep a simple log of your fish consumption to ensure you stay within recommended limits. Remember that mercury risk is cumulative, so monitoring your weekly intake is more important than daily amounts.

Measure Portion Sizes

Use a food scale or compare portions to common objects to accurately gauge serving sizes. Four ounces of cooked fish is roughly the size of a deck of cards or the palm of your hand.

Vary Your Fish Choices

Rather than eating tuna exclusively, rotate among different low-mercury fish throughout the week. This approach provides diverse nutrients while further reducing mercury exposure.

Prepare Tuna Safely

Canned tuna is convenient and already fully cooked. When preparing fresh tuna steaks, ensure they reach the proper internal temperature. Use a meat thermometer to verify they’ve reached 145°F throughout.

International Guidelines on Tuna Consumption

Many countries have issued similar recommendations regarding tuna intake during pregnancy, though specific types of tuna considered safe may vary. The underlying principle remains consistent: moderate consumption of low-mercury varieties is safe and beneficial.

If you’re living outside the United States or traveling during pregnancy, consult local health authorities for region-specific guidelines, as fish mercury levels can vary by location and fishing waters.

When to Consult Your Healthcare Provider

Discuss your diet and fish consumption with your healthcare provider during prenatal appointments, especially if:

• You ate high-mercury fish before knowing you were pregnant
• You have concerns about your omega-3 intake
• You need guidance on appropriate supplementation
• You have dietary restrictions that limit protein sources
• You experience any unusual symptoms after eating fish

Your doctor can provide personalized recommendations based on your health history, dietary patterns, and pregnancy progression.

The Bottom Line: Balancing Benefits and Risks

Yes, you can have tuna while pregnant, but making informed choices about type and quantity is essential. Canned light tuna offers the best safety profile, allowing up to 12 ounces weekly, while albacore and yellowfin should be limited to 4 ounces per week. Always avoid bigeye tuna and other high-mercury fish.

The key principles for safe tuna consumption during pregnancy are:

• Choose low-mercury varieties like canned light tuna
• Stay within recommended weekly limits
• Always eat fully cooked tuna, never raw
• Vary your fish choices throughout the week
• Consider supplementation if you don’t eat fish
• Discuss your diet with your healthcare provider

By following these guidelines, you can safely enjoy tuna’s nutritional benefits while protecting your baby’s development. The omega-3 fatty acids, protein, and other nutrients in tuna support healthy pregnancy outcomes when consumed appropriately. Making informed choices empowers you to nourish both yourself and your growing baby throughout pregnancy.

Sources:

• U.S. Food and Drug Administration – Advice About Eating Fish
• U.S. Environmental Protection Agency – Fish and Shellfish Advisories
• American College of Obstetricians and Gynecologists – Nutrition During Pregnancy
• National Institutes of Health – Omega-3 Fatty Acids and Pregnancy
• March of Dimes – Fish and Shellfish During Pregnancy