Fish in pregnancy: what is safe and what to avoid

The precious nutrients contained in fish

Fish and shellfish can be an excellent source of protein, iron and zinc, nutrients crucial for the growth and development of the fetus. In particular:

  • the omega-3 fatty acids in many fish, including docosahexaenoic acid (DHA), aid in baby’s brain development. Getting enough omega-3s can also improve your memory. Finally, an adequate intake of omega-3 fatty acids and in particular of DHA reduces the risk of depression during pregnancy and postpartum depression
  • lean proteins, of which fish is a first-rate source, are essential for the development of the skin, muscles, hair and bones of the fetus
  • a diet rich in fish can reduce the risk of heart disease by reducing blood clotting and triglyceride (blood fat) levels, as well as lowering blood pressure if you have pre-existing high blood pressure

The risk posed by mercury

Some types of seafood and fish can contain high levels of mercury. While these amounts of mercury are not a problem for most adults, special precautions are advised for pregnant women and women planning to become pregnant. By regularly eating mercury-rich fish, mercury could build up in the blood, reach the fetus and harm the baby’s developing brain and nervous system.

The risk posed by batteries and parasites

You’ve probably already heard that you should avoid sushi during pregnancy – and the same goes for any other raw fish (oysters, ceviche, smoked salmon) or undercooked fish, as they can contain bacteria and parasites (like Listeria) that are dangerous for your developing baby.

Fish that it is advisable to avoid or limit during pregnancy

Fish that, according to the US FDA, all pregnant women should avoid due to their high mercury content:

  • Royal mackerel
  • Marlin
  • Orange roughy
  • Shark
  • Swordfish
  • Malacanthidae

According to the UK’s NHS, pregnant women should eat no more than 2 tuna steaks (about 140g cooked or 170g raw) or 4 medium-sized tins of tuna per week. This is because it contains more mercury than other fish.

You should limit fatty fish because they can contain pollutants such as dioxins and polychlorinated biphenyls. If you eat too much of them, they can be harmful to your unborn baby.

You should avoid raw shellfish because they may contain harmful bacteria, viruses or toxins. These can make you sick and give you food poisoning.

What can you eat when pregnant

According to the NHS if you are pregnant you can eat:

  • cooked fish and seafood
  • smoked fish such as smoked salmon and smoked trout
  • shellfish (mussels, lobsters, crabs, prawns, scallops and clams) cooked
  • cold precooked prawns

How to prepare fish during pregnancy

Here are some tips to prepare fish properly and help reduce exposure to potential contaminants:

  • buy only fresh and properly refrigerated fish. Keep it in the fridge in an airtight container if you don’t cook it right away.
  • use separate chopping boards for meat (including fish) and fruit/vegetables.
  • cook seafood (all kinds, including shelled clams, oysters, shrimp, lobster, and scallops) until it reaches an internal temperature of 145°F; if a thermometer isn’t available, you’ll know it’s done when the meat is opaque (milky white) and the fillets flake easily with a fork.
  • clams, mussels and oysters are cooked when the shells are opened; throw out the ones that don’t.

Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.

She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform,

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