Is Swordfish Safe to Eat During Pregnancy? Mercury Level and More

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Written by Gina Wagg BA, Dip.

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Fish can often be a concerning food type for pregnant women, so it’s no wonder that you might find yourself searching for whether Swordfish is safe. 

So, is swordfish safe during pregnancy? Swordfish generally is not recommended while you’re expecting because of its high mercury content and because it is prone to parasites.

We’ll guide you through what you should know about swordfish and mercury during pregnancy and what happens if you accidentally ate some, without knowing about the concerns during pregnancy.

Is Swordfish High in Mercury?

Pregnant women are advised to avoid fish that are high in mercury. Generally speaking, the bigger the fish), the more mercury, so swordfish is immediately a red flag since they’re on the larger side.

Predatory fish also tend to have more mercury, so swordfish also fall into this category. This is not necessarily a hard rule, so you should double-check the safety of any fish while you’re expecting. 

Swordfish is considered to be high in mercury. Samples measured by the FDA showed a mean mercury concentration (ppm) of 0.995. This is very high. For comparison, shark – which is also off-limits during pregnancy – has a ppm of 0.979 and King Mackerel has a ppm of 0.73.

Meanwhile, fish such as haddock (with a ppm of 0.055) and anchovies (with a ppm of 0.016) can be eaten two to three times per week during pregnancy as they’re fairly low in mercury (source: FDA).

Swordfish can sometimes be lumped in with other “billfish” like marlin, spearfish and sailfish. They are also known as broadbills. So, be wary if you see them on a menu as these fish tend to be high in mercury too. 

grilled swordfish with mixed vegetables

Eating Swordfish During Pregnancy: Is it Safe?

Swordfish should be avoided during pregnancy, where possible. 

The main kinds of swordfish are Atlantic swordfish, Mediterranean swordfish, and Pacific swordfish but these should all be avoided. This is not only because of the high mercury content but also because this kind of fish is often contaminated with parasites. These are often killed by cooking, but it’s still a concern, especially if you were to accidentally eat slightly undercooked fish.

Most pregnant women know that high mercury fish should not be eaten during pregnancy, or rather, eaten in very moderate amounts. However, you don’t need to cut out fish entirely – in fact, most fish is an excellent source of nutritious, lean protein when you’re pregnant.

Fish is a great source of protein as well as omega-3 which is great for your brain health. In fact, the benefits of fish often outweigh what avoiding mercury altogether entails – but the best bet is to eat lower mercury fish types.

Safety and the Mercury Level of Swordfish During Pregnancy

It’s not just a clear-cut case of “all mercury is bad” – most of us already have mercury in our bodies, but during pregnancy, it’s a build-up over time that we are trying to avoid.

Research has found minimal evidence of any detrimental effects on neurobehavioural outcomes in children whose mothers had low-level mercury exposure.

Infants whose mothers consumed more fish did not need as much special handling and had better attention and girls had frequent asymmetric reflexes (source: Neurotoxicology and Teratology). 

Therefore low-mercury fish are a good choice.

Overcomsuming fish high in mercury can be harmful. Studies have found that mercury exposure can cause an accumulation in the amniotic fluid which can impact the infant’s cognitive skills.

Research also found that mothers with higher levels of mercury exposure were more likely to have premature birth. Their babies were more likely to have a low birth weight too (source: Basic & Clinical Pharmacology & Toxicology). 

It’s important to emphasize that the negative effects of mercury are generally noted with prolonged exposure over a period of time as it can accumulate in the blood. So, if you eat swordfish or another high mercury fish by accident, you don’t need to panic. Just be sure that it’s not a regular occurrence. Again, it’s a build-up that is dangerous.

organic grilled swordfish steak with a salad

Another reason to avoid swordfish in favor of other species is that it’s quite prone to parasites, as are many wild fish (source: Ices Journal of Marine Science).  This is one of the reasons why raw fish is not recommended during pregnancy. The same goes for undercooked fish, or sushi during pregnancy too.

Parasites like roundworms or even tapeworms can be found in uncooked and undercooked fish. Whether you’re pregnant or not, this can pose a health hazard (source: Seafood Health Facts).

An infection like this can even impact how well nutrients are absorbed by the body. As well as this, it can impact digestive health. Worms are typically treated with medication (source: World Health Organization). 

Studies have suggested that some kinds of worm infections during pregnancy can impact your child’s executive function (source: Journal of International Neuropsychological Society).

Cooking and freezing fish can kill parasites, however, it’s still best to give swordfish a miss while you’re expecting regardless of whether it has been cooked or not. 

What Happens if I Accidentally Ate Swordfish?

If you eat accidentally swordfish once during pregnancy, you don’t need to panic. 

Once off exposure to a high-mercury fish like swordfish is not something to stress yourself out about. The issue with mercury is that consistent exposure can lead it to accumulate in the blood. As long as you stick to low-mercury fish for the remainder of your pregnancy, you and your baby should be fine. 

When it comes to parasites, if the fish was fully cooked or had been previously frozen then it’s highly unlikely that you will get sick. Be sure to practice good food safety and eat in clean restaurants of good standing. 

If you’ve been eating swordfish often during your pregnancy, then it’s best to get your mercury levels checked out by your medical provider. Otherwise, a one-off portion of swordfish is probably fine.

I hope this reassured you about encountering swordfish during pregnancy – remember, fish is an excellent pregnancy food, if you choose low mercury options! You can read through many of our fish articles here.