Do you like eating fish or seafood but have heard it could be harmful to consume during pregnancy, leaving you wondering whether fish and seafood safe to eat during pregnancy? Read on to learn why some types of fish and seafood may be harmful during pregnancy, which types should be consumed more and less often, as well some of the benefits of including fish and seafood in your diet.

There has been caution around fish consumption during pregnancy because fish can contain mercury. Fish absorb mercury primarily from the prey they eat, who absorb it from the water they swim in. Mercury levels become more concentrated as fish higher on the food chain eat fish lower on the food chain. During pregnancy, high mercury levels are harmful to the developing fetus and are associated with permanent neurological complications, including impaired cognition, memory, attention, language and fine motor skills (1).

The types of fish that tend to be higher in mercury are not as widely consumed in Canada.

Fish With Higher Mercury Levels Include:

• • fresh/frozen tuna
  • shark
  • swordfish
  • marlin
  • orange roughy
  • escolar

Health Canada recommends that women who may become pregnant or are pregnant or breastfeeding consume no more than 150g (about 1 cup) of these fish per month (2). Albacore (white) tuna has higher mercury levels than light tuna so it is recommended to consume no more than 300g of canned albacore tuna per week, about two 170g cans (2). Additionally, fish that is imported from Asia, particularly dried fish, may contain higher mercury levels.

Fish is full of many beneficial nutrients, particularly omega-3, so Health Canada recommends that women who may become pregnant or are pregnant or breastfeeding consume fish that is low in mercury two times per week for a total of 150g (about 1 cup) per week.

Some Types of Fish That Have Low Mercury Levels and High Omega-3 Levels Include:

• • anchovy
  • capelin
  • char
  • hake
  • herring
  • Atlantic mackerel
  • mullet
  • pollock
  • salmon
  • smelt
  • rainbow trout
  • lake whitefish
  • blue crab
  • shrimp
  • clam
  • mussel
  • oysters
  • canned light tuna

Tip: If you consume fish regularly, try including different varieties of fish in your diet.

While it is important to be mindful of the types of fish and seafood you are consuming while pregnant, there are noted benefits of consuming fish that is low in mercury. As fish and seafood are high in omega-3, they can support normal fetal brain and eye development (2). In addition to omega-3, fish and seafood are great sources of protein and significant sources of vitamin D, selenium, iodine, magnesium, iron and copper (2).

Note: There is not an increased risk for pregnancy complications or poor child development in women who consume a healthy diet but do not eat fish or seafood (3).

Final Notes from The Nest

Moderate consumption of fish and seafood that is low in mercury can be part of a healthy diet during pregnancy and provides many beneficial nutrients. Be mindful of the sources of fish and seafood you are eating while trying to include a variety of fish and seafood in your diet.

Article written by Kaitlyn Thorp-Levitt

References

1. Dietitians of Canada. (2019, August 26). Are there safety concerns for the ingestion of fish in women who are pregnant, planning to become pregnant or breastfeeding related to mercury contamination? Practice-based Evidence in Nutrition ^® [PEN]. Retrieved June 19, 2020, from https://www-pennutrition-com.proxy1.lib.uwo.ca/KnowledgePathway.aspx?kpid=3043&pqcatid=146&pqid=3207
2. Health Canada. (2007, March 26). Mercury in Fish. Government of Canada. Retrieved June 19, 2020, from https://www.canada.ca/en/health-canada/services/food-nutrition/food-safety/chemical-contaminants/environmental-contaminants/mercury/mercury-fish.html
3. Health Canada. (2009, April 28). Prenatal Nutrition Guidelines for Health Professionals – Fish and Omega-3 Fatty Acids. Retrieved June 19, 2020, from https://www.canada.ca/en/health-canada/services/publications/food-nutrition/prenatal-nutrition-guidelines-health-professionals-fish-omega-3-fatty-acids-2009.html