You can easily eat safely 2-3 portions of fish per week. We generally say that fish is consumed for protein, and you can get your DHA and from synthetic or other forms of 'fish oil.' You need 300 mg per day of DHA if you are pregnant. You can check your prenatal vitamins with your gyno for advice if you aren't sure of the content. You need it now, your baby won't be able to catch up if you don't get this during your pregnancy, although proper nutrition after pregnancy is important for the child of course. Eyes and brain development are what is most valuable about the DHA. Mercury in fish, however, can have a negative impact on fetal brain development. The "S" fish to eat: Shrimp, salmon, scallops, sardines. The "S"-fish to avoid: shark, swordfish. The mercury content is the reason to avoid certain fish. Other low in mercury content fish include tilapia, tuna (canned-light), cod, and catfish. The American College of Obstetricians and Gynecologists updated their advisory about fish in June of 2017. In this advisory they warn against any under cooked food including seafood and eggs.