11 Foods and Beverages to Avoid During Pregnancy

2. High-Mercury Fish


Mercury is a highly toxic element. It has no known safe level of exposure, and is most commonly found in polluted water (1).

In higher amounts, it can be toxic to the nervous system, immune system and kidneys (2).

Since it is found in polluted seas, large fish that live in these oceans can accumulate high amounts of mercury.

Therefore, pregnant women are advised to limit their consumption of high-mercury fish to no more than 1-2 servings per month (3, 4).

High-mercury fish include:

  • Shark.
  • Swordfish.
  • King mackerel.
  • Tuna (especially albacore tuna).

However, it is important to note that not all fish are high in mercury — just certain types.

Consuming low-mercury fish during pregnancy is very healthy, and these fish can be eaten up to 2 times per week. Fatty fish is high in omega-3 fatty acids, which are important for the baby.

Bottom Line: Pregnant women should not eat high-mercury fish more than 1–2 times each month. This includes shark, swordfish, tuna and mackerel.

Undercooked or Raw Fish

Raw fish, especially shellfish, can cause several infections. These include norovirus,Vibrio, Salmonella, Listeria and parasites (5, 6, 7).

Some of these infections only affect the mother, leaving her dehydrated and weak. Other infections may be passed on to the unborn baby with serious, or even fatal, consequences (5, 6).

Pregnant women are especially susceptible to Listeria infections. In fact, pregnant women are up to 20 times more likely to get infected by Listeria than the general population (8).

This bacteria can be found in soil and contaminated water or plants. Raw fish can become infected during processing, including smoking or drying.

Listeria can be passed to an unborn baby through the placenta, even if the mother is not showing any signs of illness. This can lead to premature delivery, miscarriage, stillbirth and other serious health problems (9).

Pregnant women are therefore advised to avoid raw fish and shellfish. This includes many sushi dishes.

Bottom Line: Raw fish and shellfish can be contaminated with bacteria and parasites. Some of these can cause adverse health effects and harm both the mother and unborn baby.