Although lobster doesn’t contain an extremely high amount of mercury, it still does contain this harmful substance. Excess of mercury can accumulate in the mother’s system and have a direct effect on the baby’s brain and nervous system. In fact, delayed effects of mercury include mental retardation and improper nervous system development during later stages of the baby’s growth. Therefore, it is important to eat this crusty seafood in moderation. It is also important to mention here that pregnant women must refrain from eating raw or undercooked lobster, and clean and cook the lobster thoroughly before eating, preferably till it is pearly opaque.