Tuna salad sandwiches are generally safe to eat during pregnancy, but there are certain precautions you need to take. High levels of mercury, which is prevalent in tuna fish, can harm your baby's developing nervous system. Therefore, limiting your tuna intake to two or three servings per week is essential. Additionally, make sure to choose a can of tuna that is labeled "light" or "chunk light" because it contains less mercury than "white" or "albacore" tuna.