Why Is Mercury So Dangerous When Pregnant?

We’ve all heard that eating fish is an important part of our diet, especially when pregnant, but there are also warnings about eating too much fish during pregnancy. So how much is safe to eat and what types of fish should you avoid?

RELATED: Check out these other foods to avoid whilst pregnant

What is mercury and methyl mercury?

Mercury is a chemical element that occurs naturally in the environment in the air, water and soil. When mercury accumulates in the water it is turned into methyl mercury which fish absorb as they feed in the waters. Over time the mercury levels build up in the fish, some more than others depending on what they eat, and when we catch and eat these fish we consume this mercury too.

What types of fish have the highest levels of mercury? 

Most fish and shellfish contain some mercury but larger fish at the top of the food chain that have been living for a long time generally have higher levels because they’ve had more time to accumulate the mercury. Fish including swordfish, barramundi, orange roughy, shark and king mackerel seem to pose the greatest risk to pregnant women.

How can mercury harm my baby?

Although research is ongoing it appears that consuming high levels of methyl mercury during pregnancy can harm your baby’s brain and nervous system. The effects may not be apparent for years after your child is born but can seriously affect your child’s cognitive skills, language, motor skills and vision.

Why shouldn’t I just give up eating fish altogether?

If you choose to eat fish with low levels of mercury during pregnancy then the risks of harming your baby are very slim and you’ll also be reaping the benefits from eating fish. The fatty acids found in fish are vital for your unborn baby’s brain and eye development so don’t give up on it entirely.

What fish are safe to eat during pregnancy?

Some types of fish that are low in mercury as well as high in healthy fats are mackerel, rainbow trout, salmon and sardines. Shellfish with low levels of mercury include prawns, lobster and oysters. It is recommended that pregnant women eat no more than three serves of fish per week (in the low level of mercury category) and if they do choose to eat fish in the high mercury level category then it should be restricted to one serve per fortnight.

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Five Spice Salmon With Broccolini And Asparagus

Salmon is packed full of omega-3 fatty acids, essential for the health of your brain, your heart and could potentially reduce the risk of chronic diseases and some types of cancer. This recipe is healthy and incredibly simple so put it on your menu this week!


4 180g salmon fillets, pin boned, skin on

1 tsp Chinese five spice

¼ cup hoisin sauce

1/3 cup peanut oil

2 cloves garlic, crushed

4cm piece of ginger, cut into thin matchsticks

1 red onion, thinly sliced

1 bunch broccolini

1 bunch asparagus

40g baby spinach

1 cup basil leaves

1 tsp sesame oil


  1. In a bowl combine five spice, hoisin sauce and 2 tablespoons peanut oil then season with salt and pepper.
  2. Add salmon to bowl and gently toss to coat the salmon in mixture.
  3. Heat 1 tablespoon peanut oil in a large frying pan over high heat.
  4. Cook salmon to your liking in batches then transfer to a plate.
  5. Heat remaining peanut oil in saucepan over high heat then add garlic, ginger and onion.
  6. Stir fry for 2 minutes or until onion is soft.
  7. Add broccolini and asparagus then stir fry for a further 3 minutes or until vegetables are tender.
  8. Remove from heat and stir in spinach, basil and sesame oil.
  9. Divide the vegetables among plates then place fish on top to serve.
  10. Serve with brown rice if desired.

Image via taste.com.au