As a low-fat source of protein and essential fatty acids that have been shown to promote healthy brain development in unborn babies, many types of fish are recommended as a healthy part of your diet during pregnancy. That said, there are risks from high levels of mercury in certain fish (mercury may affect the development of your baby's brain and nervous system) so it's important to pay attention to what types of fish you eat and how often you have them.
The recommendations for what types of seafood and how much is safe to eat change constantly, so it's important to check with your doctor for the most up-to-date advice. But generally speaking, it's a good idea to aim for up to 12 ounces a week (that's about two to three servings) of low-mercury fish like salmon, shrimp, and canned light tuna (skip or limit albacore, which is moderately high in mercury). Steer clear of swordfish, shark, king mackerel, and tilefish, because these large predator fish have the highest levels of mercury.