Halibut is safe to eat during pregnancy, but in limited amounts. The FDA and EPA classify halibut as a “Good Choice” for pregnant women, which means you can safely eat one serving (4 ounces) per week. That’s a step below the “Best Choices” category, where fish like salmon, shrimp, and tilapia allow for two to three servings weekly. The distinction comes down to mercury: halibut contains moderate levels that are fine in small quantities but can accumulate if you eat too much.
Why Halibut Has a Weekly Limit
Halibut contains an average mercury concentration of 0.241 parts per million, according to FDA testing data. That places it solidly in the moderate range. For comparison, low-mercury fish like salmon and shrimp typically measure well under 0.1 ppm, while high-mercury fish like swordfish and shark exceed 0.9 ppm. Halibut sits in the middle, which is why it earns the “Good Choice” label rather than “Best Choice.”
Individual halibut fillets can vary widely. FDA records show mercury levels in halibut ranging from undetectable all the way up to 1.52 ppm. Larger, older fish tend to accumulate more mercury because they’ve had more years of exposure. You can’t control which fish ends up on your plate, so the one-serving-per-week guideline builds in a safety margin to account for that variability.
What Mercury Does to a Developing Baby
The concern with mercury during pregnancy is specifically about methylmercury, the form found in fish, and its effect on the fetal brain. The developing brain is the primary target for methylmercury toxicity. Research tracking children from before birth through adolescence has documented measurable effects from prenatal exposure, including slower motor speed, reduced attention, and delayed language development.
A long-running study in the Faroe Islands followed children exposed to methylmercury in the womb and found that at age 7, the clearest deficits appeared in attention, language, and verbal memory. By age 14, these effects persisted. Participants with higher prenatal exposure had poorer ability to recall names of objects, even when given cues. The researchers concluded that methylmercury’s effects on brain development appear to be widespread across multiple brain functions and permanent.
This is why limits exist, not because any single serving of halibut is dangerous, but because consistent overexposure during the months when fetal brain structures are forming can leave lasting traces.
Why Fish Still Matters During Pregnancy
Avoiding fish entirely during pregnancy would be a mistake. Fish provide omega-3 fatty acids, particularly DHA, that are critical building blocks for your baby’s brain and eyes. DHA makes up roughly 97% of all omega-3 fats in the brain and 93% in the retina. During the third trimester, the fetus accumulates about 50 to 70 milligrams of DHA per day, all of which comes from the mother’s intake.
The dietary goal for omega-3 fatty acids during pregnancy is 650 milligrams per day, with at least 300 of that coming from DHA. Fish also provide iron, iodine, choline (which supports spinal cord development), vitamin D, vitamin B12, selenium, and high-quality protein. The FDA’s guidance is designed to help you get these benefits while keeping mercury exposure low: aim for 8 to 12 ounces of seafood per week total, choosing mostly from lower-mercury options and treating halibut as an occasional pick rather than a staple.
How to Fit Halibut Into Your Weekly Fish Intake
If you eat a 4-ounce serving of halibut in a given week, that counts as your “Good Choice” serving. You shouldn’t add another “Good Choice” fish (like mahi-mahi or snapper) that same week. However, you can pair your halibut serving with additional servings of “Best Choice” fish like salmon, sardines, or shrimp to reach the 8-to-12-ounce weekly target.
A practical weekly plan might look like two servings of salmon plus one serving of halibut, or one halibut fillet alongside a couple of shrimp meals. The key is variety. Eating different types of fish spreads out your exposure to any single contaminant while maximizing the range of nutrients you and your baby receive.
Cooking Halibut Safely
Raw or undercooked halibut is off the table during pregnancy. Cook all halibut to an internal temperature of 145°F (63°C). You’ll know it’s done when the flesh separates into flakes easily and looks opaque, milky white throughout. This eliminates the risk of bacterial and parasitic infections that pregnant women are more susceptible to. Halibut sushi, ceviche, or any preparation that leaves the fish raw or partially cooked should be avoided until after delivery.
What About Selenium’s Protective Effect?
You may have heard that selenium in fish can protect against mercury’s harmful effects. Halibut does contain selenium, and the theory is appealing: a natural mineral in the same food counteracting the toxin. However, research has not supported this idea. A study examining selenium and methylmercury levels in cord blood found that even though selenium was present at concentrations roughly 10 times higher than methylmercury, it did not provide a meaningful protective effect against neurotoxicity. The safest approach remains keeping mercury intake low rather than relying on selenium to offset it.