Answered by Errol Norwitz, M.D., Ph.D. Dr. Norwitz is internationally recognized for his work in high-risk obstetrics. He is the Chair of Obstetrics & Gynecology at Tufts Medical Center, and a Professor at Tufts University School of Medicine in Boston. He is board certified in Obstetrics & Gynecology and Maternal-Fetal Medicine.
Fish is a nutritious and healthy source of lean protein. It is also low in saturated fat and high in omega-3 fatty acids. Most dietitians or nutritionists suggest you eat two servings of fish each week, which amounts to around 12 ounces.
It is important to avoid eating multiple servings of large fishes (such as swordfish, shark, tuna, marlin, sea bass, mackerel, and pike) every week during pregnancy because they contain mercury. Mercury accumulates in the atmosphere and is then widely distributed throughout the planet in rainwater. During a fish’s life cycle, mercury accumulates in its body as there is no way to break it down or excrete it. Large fish feed on small fishes and, as such, the mercury levels in their body increases. Studies have shown that large amounts of mercury can damage your baby’s developing nervous system, which might result in future learning disabilities and other developmental disorders.
Some fish have less mercury than others. Examples of fish safe to eat during pregnancy include salmon, sardines, farmed trout, catfish, flounder, and haddock. It is a good idea to stay away from fish sushi or any raw fish during pregnancy because most of the fish used to prepare sushi contain higher levels of mercury. Vegetable sushi is fine. The other option is to check with your fresh local fish advisory.
In general, precaution should be taken when preparing fish to prevent infection. Try to keep the ten-minute rule in mind. This means finding the thickest part of the fish and cooking it for ten minutes per inch. Also, try to avoid freshwater fish caught by friends and family. If you want to read more about the safety of fish, check out the EPA’s website at http://www.epa.gov/waterscience/fishadvice/advice.html