Is ahi tuna safe to eat when pregnant? (3 risks)

In this article, we will discuss the risks of eating ahi tuna when pregnant, the benefits of eating ahi tuna when pregnant, how to safely consume ahi tuna and the possible alternatives to ahi tuna.

Fish is considered a healthy food and an important source of fatty acids and proteins for all individuals. However, eating ahi tuna when pregnant can be a risk due to some factors, which will be discussed in this article.

Is ahi tuna safe to eat when pregnant?

Yes, ahi tuna may be safe to eat when pregnant. However, due to the possible risk of an excessive concentration of mercury in this fish, the consumption of ahi tuna should be limited during pregnancy (1, 2). 

In addition, there is a possible risk related to the presence of scombrotoxin in the Tuna species, which can lead to poisoning when consumed (3). 

Finally, ingesting fish is always a risk of foodborne diseases. Due to the perishability of fish, it can be easily spoiled by pathogenic microorganisms. The ingestion of contaminated fish can lead to infections (4).

What are the risks of ahi tuna when pregnant?

The risks of eating ahi tuna when pregnant are summarised below (1, 2, 3, 4). They refer not only to the mother´s health but also to the child´s health, as the health of pregnant women affects the health of the unborn indirectly.

Ingestion of mercury and other heavy metals

Fish and seafood may contain mercury in high concentrations, especially fish that are predators, such as tuna.

Studies report high amounts of mercury and other heavy metals in samples of ahi tuna imported from Asian countries and commercialised in Europe and the United States.

The symptoms of the ingestion of heavy metals are damage to bones and organs, including the liver and kidneys, intelligence deficiencies, damage to the reproductive system and cancer. The unborn child is more susceptible to suffering damage.

Poisoning by scombrotoxin or histamine intoxication

Scombrotoxin can be present in fish species of the family Scombridae, which includes tuna when the fish is poorly handled or stored. Bacterial activities, which cause protein deterioration, generate high concentrations of histamine.

Possible symptoms of scombrotoxin poisoning are diarrhoea, headache, urticaria, vomiting, and palpitations. In more severe cases, it can lead to the loss of consciousness.

Foodborne diseases

Fish are hosts of pathogenic microorganisms, especially bacteria and parasites. When fish is not properly handled or stored or not sufficiently cooked, these microorganisms develop and remain in the fish in unsafe amounts.

Consuming contaminated fish may lead to foodborne diseases and symptoms such as vomiting, diarrhoea, nausea, abdominal pain, and fever. 

It is important to consider that pregnant women are more susceptible to foodborne diseases and poisoning, due to their weakened immune system during pregnancy (5).

Are there benefits of eating ahi tuna when pregnant?

Yes, there are benefits of eating ahi tuna when pregnant. Like other fatty fish species, Ahi tuna is a source of protein, omega-3 fatty acids, vitamins and minerals and its consumption is recommended during pregnancy (4, 5).

Tuna is rich in omega-3 fatty acids, including eicosapentaenoic acid and docosahexaenoic acid (6). These fatty acids are essential for human health and important for the development of the brain.

They act also as anti-inflammatory compounds and their ingestion is related to a higher risk of developing cardiovascular diseases.

Therefore, the consumption of 2 to 3  servings (4 ounces each) of fish is recommended by the Food and Drug Administration (FDA) (5). However, pregnant women should look for fish sources of low mercury. 

How to safely consume ahi tuna when pregnant?

To safely consume ahi tuna when pregnant, reduce the ingestion frequency to less than one 4-ounce serving a week.

Ahi tuna may contain a high level of mercury and other heavy metals that may affect the health of both mother and unborn child (1, 2).

Ahi tuna, also known as yellowfin tuna (1), is considered to have moderate amounts of mercury in its concentration and to be a good fish option during pregnancy, according to the FDA (5).

However, in recent studies, high amounts of heavy metals were found in ahi tuna in samples marketed in several countries.

Other safety tips for eating ahi fish when pregnant?

Other safety recommendations regarding fish consumption are the following (1, 2, 3, 4, 5):

  • Purchase fresh fish with no signs of spoilage and do not consume cooked fish if any signs of spoilage are present.
  • Spoilage in fish is identified by an unpleasant odour, such as ammoniacal, rancid or fermented. Other signs of spoilage are discolouration, gas production, and loss of texture.
  • Consume fish within its shelf life. Fresh fish should be consumed or cooked in 2 days, while cooked fish can be stored in the refrigerator for 3 days or freezer for 3 months.
  • Keep fish stored at temperatures of 40 °F (4 °C) or below at all times to prevent microbial development
  • Cook fish to a minimal internal temperature of 145 °F (63 °C) till the flesh is firm and clear

What are safe alternatives to ahi tuna when pregnant?

Safe alternatives to ahi tuna when pregnant are fish species with low concentrations of heavy metals. Usually, non-predator and smaller fish species are less prone to contain high levels of mercury and other contaminants (1, 2, 3).

In a study, fish samples obtained from the Californian market were analysed regarding their concentration of omega-3 fatty acids and heavy metals (7).

Fish species with high amounts of omega-3 fatty acids and low concentrations of contaminants were Anchovy and Mackerel, while Sardine and Salmon, also rich in omega-3 showed high levels of contaminants (7). 


In this article, we discussed whether eating ahi tuna is safe when pregnant, the risks related to the consumption of ahi fish and the safety recommendations for consuming ahi fish during pregnancy.

Ahi fish, also known as yellowfin tuna, can contain high levels of mercury and other heavy metals of health concern. In this way, it should be consumed in moderation during pregnancy.

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