Quick Learning Summary
- Consuming seafood is better than not consuming it at all since it provides so many nutrients important for pregnancy.
- The fish mentioned here are not the only options you can consume, but they are great options that are low in mercury.
- Be sure to cook seafood thoroughly, especially shellfish.
- There's really no need to calculate the exact amount of seafood you are consuming per week, as upwards of 100 oz/week has been shown to provide benefits in the literature. This is great news if you're a pescatarian!
Seafood is sometimes an 'unclear' topic during pregnancy, but I want to make it very clear: if you are not allergic to seafood, eat it regularly during pregnancy.
In fact, fish is one of the best foods you can eat during pregnancy. It's packed with protein, omega-3 fatty acids, and other essential nutrients like iodine and vitamin D that support your baby's development.
The two risks of seafood consumption are mercury levels and food safety precautions. While these are both important, they are not reasons to cut seafood from your diet.
We will discuss these more below. Also note, the list of fish below is not exhaustive; you can include other seafood options in your diet.
What is Mercury?
According to the World Health Organisation (WHO), mercury is one of the top ten chemicals of major public health concern. But why? How are we exposed to mercury, and what are the risks?
Mercury is a naturally occurring element found in soil, water, and air. Mercury can be absorbed by fish and shellfish. If a big predator fish eats a smaller fish that contains mercury, the big fish will acquire the mercury levels. This is called bioaccumulation (1, 2). The level of mercury in fish is dependent on their size and local environment.
Similarly, you can be exposed to mercury by eating fish and shellfish that contain mercury.
It is important to note that cooking processes do not decrease the mercury levels in fish or shellfish (1).
How Can Mercury Affect Pregnancy Outcomes?
Most people are exposed to mercury, but at very low levels that do not pose a health risk. However, fetuses are more sensitive to the effects of methylmercury (1).
High levels of mercury during pregnancy may cause (2):
Stillbirths · Craniofacial malformations · Neural tube defects · Brain damage · Infantile cerebral palsy
When the mother eats fish or shellfish that contain methylmercury, the mercury is then passed through the placenta to the fetus (2, 4). This can affect the brain and nervous system development. Later in life, this could threaten their memory, attention, language, and fine motor and visual-spatial skills (4). High mercury exposure during pregnancy is also associated with poor birth weight (5).
Low levels of mercury during pregnancy have not been associated with adverse effects in children (6). In fact, one study found that mothers who consumed white and oily fish during pregnancy did not have mercury levels high enough to harm early development, child behavior, or their IQ (7).
How Much Fish Is Safe to Consume?
Most people are not consuming enough fish.
Some studies show that consuming slightly more fish than the standard recommended amount is associated with better pregnancy outcomes, but every mother has different nutritional needs.
While some sources recommend 12 oz. or less of seafood during pregnancy, this is not entirely supported by the evidence. Scientific evidence continues to show better cognitive outcomes in children whose mothers ate more seafood during pregnancy, even way past the 12 oz/week mark (i.e., some ate > 100 oz/week).
Hibbeln et al. (2019) reviewed 44 studies on the relationship between seafood consumption during pregnancy and brain development – they found that fish in the diet has benefits that far outweigh the risk of increased mercury levels.
So, yes, it is safe to eat low-mercury fish during pregnancy. There are plenty of fish in the sea for you to enjoy, and only a short list of avoids like shark, swordfish, king mackerel, orange roughy, marlin, and bigeye tuna.
There are also significant benefits for mothers, such as a reduced risk of cardiovascular disease and other chronic diseases.
The level of mercury in fish is dependent on their size and local environment.
Why Omega-3s Are Essential During Pregnancy
Omega-3 fatty acids, particularly DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), play a crucial role in your baby's development. DHA is involved in developing your baby's brain. It is also a key structural component of the retina, which is important for proper eye development.
One review found a 42% reduction in early preterm birth (< 34 weeks' gestation) and 11% reduction in preterm birth (< 37 weeks' gestation) with omega-3 fatty acid supplementation. Another study found omega-3 intake to be inversely associated with preterm birth risk.
Low Mercury Seafood Options
Salmon
One of the more popular and favored fish, salmon, is known for its multiple health benefits, delicate flavor, and beautiful pink color. It also contains low mercury, especially if you can find Atlantic Salmon. Although not completely necessary, if you buy wild-caught salmon instead of farmed salmon, it contains more omega-3 fatty acids!
Check out the full note on salmon in the app for a more detailed breakdown of wild vs. farmed salmon.
Just two servings a week of this oily fish is enough to meet the recommended amounts of EPA and DHA during pregnancy, but you can eat more than this if it is one of your faves.
Shrimp
Shrimp is another type of seafood rich in omega-3 fatty acids. Shrimp also contains good amounts of iron, zinc, and iodine, all important nutrients for pregnant women. Iron is vital for increasing red blood cells and preventing anemia, while iodine plays an important role in the formation of thyroid hormones for you and your growing baby.
Ceviche is often made with uncooked shrimp; the citrus and salt do not cook the fish, so it must be heated to ensure maximum safety.
Anchovies
Anchovies are a surprisingly common pregnancy craving, but are they safe during pregnancy? Despite the many pregnancy food myths against seafood, the answer is yes! Anchovies are tiny fish and therefore have very low levels of mercury, a win for pregnant women. Research shows that eating anchovies can lower blood pressure, regulate triglyceride levels, and reduce the risk of stroke.
Sardines
Sardines, like anchovies, are among the lowest-mercury fish, even though they may not be at the top of the list of favorite fish. Sardines are also very similar to herring, which is another great option. They're perfectly safe to eat during pregnancy and recommended if you can stomach them. Sardines have many benefits for pregnancy thanks to their high levels of vitamin B12, omega-3 fatty acids, calcium, iron, zinc, and protein.
Squid
Squid, also known as calamari, is only safe for pregnant or breastfeeding women when cooked properly, as with most fish and shellfish. So, ordering calamari as an appetizer at your favorite restaurant is still okay. Squid is packed full of nutrients, like most fish. Some of the most notable ones are protein, iron, vitamin E, copper, B12, selenium, and zinc! If you like squid, include it in your diet while pregnant.
Cod
Cod is one of the more popular fish and is often used for the dish 'fish and chips.' It has a mild flavor, so it can be a good option for those who aren't fish fanatics. Cod is a great choice if you want to up your protein intake, especially in the third trimester. It's low in mercury and contains iron, selenium, potassium, and calcium.
However, since cod is a lean fish, it does not have the amount of omega-3s as salmon, sardines, or herring, for example. If cod is the only fish you like, you may want to consider an omega-3 supplement. We love this one!
Trout
Like cod, trout is a type of fish that is milder in taste and good for those who don't particularly love any sort of 'fishy' taste. The good news about trout is that it has more omega-3 fatty acids than cod, so give trout a go if you are trying to conceive or are pregnant. Try trout if you need to boost your protein intake or don't eat much meat, because it is a great source of vitamin B12.
Scallops
Scallops are among the lowest-mercury shellfish, so they are a great option. If not cooked thoroughly, scallops can pose a food safety risk; make sure they reach 145°F. Scallops are a good source of protein, minerals like magnesium, omega-3 fatty acids, and vitamin B12. With their delicate and moderately sweet taste, you'll want to make the most of your weekly servings!
Skipjack and Canned Light Tuna
While albacore and yellowfin tuna contain higher mercury levels, skipjack and canned light tuna are the two varieties of this seafood that are safe for pregnancy. We have a full guide dedicated to tuna here and one on mercury here. While the largest forms of tuna should be limited or avoided, smaller varieties are safe to consume during pregnancy and are also a super-easy way to get quality protein.
Tuna is beneficial for pregnant women thanks to its high levels of omega-3 fatty acids, vitamin D, and selenium. A quick tuna salad is so easy for a take-to-work lunch when pregnant. Be sure to only buy BPA-free canned tuna when you can!
Clams or mussels
Clams and mussels are safe to eat during pregnancy as long as you ensure they're fully cooked! Believe it or not, clams are a truly nutritious food! They're rich in minerals, protein, vitamins D and B, iron, and omega-3 fatty acids. Just always be certain that you're eating cooked clams, mussels, and oysters.
Ryann Kipping
Licensed Dietitian & Founder of The Prenatal Nutrition Library
Prenatal dietitian with a Master's in Public Health and author of The Feel-Good Pregnancy Cookbook. Founder of The Prenatal Nutrition Library App.
