Fish consumption during pregnancy often raises questions. While fish offers essential nutrients for both the pregnant individual and the developing fetus, concerns about contaminants like mercury are also present. Understanding which types of fish to choose and in what quantities is important for balancing these benefits and potential risks.
Nutritional Contributions of Fish
Fish provides several important nutrients that support a healthy pregnancy and fetal development. Omega-3 fatty acids, particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are abundant in many fish varieties. These fatty acids are crucial for the development of the baby’s brain, eyes, and central nervous system.
Fish also offers high-quality protein, essential for the growth of maternal and fetal tissues. Many fish contain vitamin D, important for bone health, and iodine, which supports proper thyroid function and neurological development. Fish can also provide iron and zinc, minerals important for overall maternal health and fetal growth.
Understanding Mercury Content
Mercury is a naturally occurring element found in the environment that can accumulate in the aquatic food chain, primarily as methylmercury. This organic form of mercury is readily absorbed by fish and can then be transferred to humans when consumed. Methylmercury is a neurotoxin, meaning it can harm nerve tissue.
During pregnancy, methylmercury is a concern because it can cross the placenta and affect the developing fetal brain and nervous system. The developing brain is particularly sensitive to its effects, even at levels that may not cause noticeable symptoms in the pregnant individual. High levels of prenatal methylmercury exposure have been associated with neurological issues in children, including deficits in attention, behavior, cognition, and motor skills.
Recommended Fish Choices and Serving Sizes
For pregnant individuals, it is generally recommended to consume 8 to 12 ounces of a variety of low-mercury seafood per week. This amount typically translates to two to three servings, with one serving being about 4 ounces. Choosing fish from the “Best Choices” category, as identified by health authorities, helps maximize nutritional benefits while minimizing mercury exposure.
Examples of fish that are considered low in mercury and are good choices include salmon, cod, shrimp, and light canned tuna. Other suitable options include tilapia, pollock, catfish, sardines, anchovies, herring, and freshwater trout. While canned light tuna is a good option, canned white (albacore) tuna may contain higher mercury levels and should be limited to no more than 6 ounces per week.
Fish to Limit or Avoid
Some types of fish contain higher levels of mercury and should be limited or avoided entirely during pregnancy. These fish tend to be larger, longer-lived, and predatory, accumulating more methylmercury over their lifespan.
Fish to avoid include shark, swordfish, king mackerel, and tilefish from the Gulf of Mexico. Other high-mercury fish include marlin, orange roughy, and bigeye tuna. Staying informed about local fish advisories is important, especially when consuming fish caught recreationally, as contaminant levels can vary by location.