Yes!
Because of high-levels of mercury, pregnant women should avoid shark, swordfish, king mackerel and tilefish. Smaller fish are usually safe, such as light tuna, salmon, pollock, and catfish. Up to 12 ounces per week of these fish is considered safe.
In fact, regular consumption of fish (and their omega fats) has been associated with lower rates of preterm labor and other complications of pregnancy.