It is generally believed that eating fish is beneficial for pregnant women and their fetuses. However, in recent years, the United States has identified four types of fish (shark, swordfish, king mackerel, and tilefish) with high mercury levels, which should not be consumed by pregnant women, women planning to become pregnant, breastfeeding mothers, and young children. Later, certain seafood with excessive mercury levels was also added to the blacklist, including tuna, Gulf oysters, sea bass, Atlantic cod, marlin, sailfish, and white croaker, in order to protect women and children from mercury poisoning. Authorities also recommend that pregnant women reduce their consumption of canned tuna, swordfish, cod, and haddock, as these canned fish also have high mercury levels, and consumption should be limited to once a month. The U.S. authorities point out that pregnant women can safely consume seafood such as farmed trout and catfish, shrimp, flounder, Pacific salmon, yellowtail, Atlantic blue crab, and black sea bass.
Studies have shown that excessive absorption of mercury by the fetus in the mother's body can affect brain and nerve development, leading to learning disabilities and delayed intellectual development, among other long-term effects.
