1. Seafood that should be avoided during pregnancy. During pregnancy, since seafood may contain a large amount of mercury and other harmful substances, it is recommended that pregnant women avoid eating the following seafood: 1. Oysters: Oysters are one of the common seafood, but They may contain bacteria and viruses that can cause damage to the fetus. 2. Shark: Shark meat contains high concentrations of mercury, a heavy metal that can cause damage to fetal nerves. 3. Goldfish: Goldfish are also marine species that contain high concentrations of mercury.