Safety Status: Avoid Entirely
King Mackerel is a high-mercury fish that must be strictly avoided during pregnancy.
The U.S. Food and Drug Administration (FDA) and the U.S. Environmental Protection Agency (EPA) classify King Mackerel on their list of “Choices to Avoid” for pregnant individuals, women planning to become pregnant, and young children.
King Mackerel is a large, predatory fish found in coastal waters. Because of its large size, long lifespan, and diet of smaller fish, it accumulates high concentrations of methylmercury in its tissues over time (bioaccumulation).
While smaller varieties of mackerel are safe, King Mackerel consistently shows mercury levels that exceed safe consumption thresholds for fetal safety.
The Difference Between Mackerel Species
It is critical to distinguish between different types of mackerel, as their safety profiles are completely opposite:
- King Mackerel (Avoid): High-mercury, large predator.
- Spanish Mackerel (Moderate): Intermediate mercury levels; should be limited to no more than one serving per week, or avoided.
- Atlantic or Chub Mackerel (Safe): Small, short-lived fish that are exceptionally low in mercury. Atlantic mackerel is one of the best sources of beneficial Omega-3 fatty acids (DHA and EPA) and is highly recommended.
Risks of Prenatal Mercury Exposure
Methylmercury absorbed from maternal food intake enters the maternal bloodstream and easily crosses the placenta.
A developing fetus is highly sensitive to mercury, which can interfere with the normal growth of brain cells and the nervous system.
Even if the mother shows no symptoms of mercury toxicity, high prenatal exposure can lead to long-term cognitive and physical developmental deficits in the child, affecting coordination, attention, and language acquisition.
Safe Seafood Guidelines
You can safely consume seafood by sticking to the FDA’s “Best Choices” list. Eat 8 to 12 ounces (2 to 3 servings) of low-mercury fish per week, such as:
- Atlantic Mackerel: Highly nutritious, rich in healthy fats, and low in mercury.
- Salmon: Excellent source of DHA.
- Sardines: Safe, nutrient-dense, and low in mercury.
- Shrimp or Cod: Low-risk seafood choices.
Safe Alternatives
Atlantic Mackerel, Chub Mackerel, wild-caught salmon, or sardines.
OB-GYN Clinical Tip
Do not eat King Mackerel. If ordering mackerel at a restaurant or buying it canned, always verify the specific species. Atlantic Mackerel is safe and healthy, whereas King Mackerel is dangerous.
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