Is it safe to eat fish during pregnancy?

Many women are leery to consume fish during pregnancy due to concerns regarding mercury consumption and the effect on their developing baby.

Studies, however, show that it important to consume fish which contain omega-3 fatty acids during pregnancy and when breastfeeding.  These polyunsaturated fatty acids are vital in fetal and newborn central nervous system (brain) and visual development.

There are three different types of omega-3 fatty acids.  The first, alpha-linolenic acid (ALA) can be found in some vegetable oils (e.g. canola), nuts (e.g. walnuts) and seeds (e.g. flax seeds). Our bodies can convert ALA into a second type of omega-3 fat, docosahexaenoic acid (DHA).  The third fatty acid is eicosapentaonoic acid (EPA).  DHA and EPA can only be found in animal fats.  The best source is fatty fish (e.g. salmon).  DHA is also found in eggs. 

In order to obtain the most benefit from consuming fish, but limit the risk of mercury exposure, both Health Canada and Canada’s Food Guide recommend that women consume about 5 ounces of fish per week (a typical serving size of fish is 3 to 6 ounces). Fish with lower levels of contaminants that are commonly found in the grocery store include salmon, trout, haddock, canned light tuna, pollock and sole. 

Some fish contain higher levels of mercury, however, and should only be consumed approximately once per month. Examples include: fresh and frozen tuna, shark, swordfish, marlin, orange roughy and escolar. Women who eat canned tuna should limit “albacore” or “white” tuna to 10 ounces per week (approximately 2 small tins), however Health Canada has not established a maximum limit on “skipjack”, “yellowfin” or “tongol” canned tuna. 

Fish should always be thoroughly cooked, including smoked products, to reduce the risk of contracting listeriosis which can harm a woman and her baby.

Some women may wish to take a fish oil supplement before or during pregnancy, or while breastfeeding.  Keep in mind that this is not the equivalent of eating fish in your diet (i.e. not a replacement).  Look for a supplement with a Natural Product Number (NPN) on the label which demonstrates government approval. Cod liver oil should be avoided, as this also supplements Vitamin A.  Vitamin A is already found in prenatal or multivitamins and taking both supplements could lead to an overdose of this vitamin. 

For further information, ask your doctor to see if a fish oil supplement is recommended for you. Or for more details on the above information and to check out specific dietary nutrients found in some fish, visit http://www.hc-sc.gc.ca/fn-an/pubs/nutrition/omega3-eng.php