Many women avoid eating fish during pregnancy for fear of consuming high levels of mercury that can accumulate in their bloodstream and impair their baby's developing brain and nervous system. The Food and Drug Administration (FDA), which has long warned pregnant women and nursing mothers about the dangers of mercury and other heavy metals found in fish, however, is revising its recommendation on fish consumption.

On Tuesday, the FDA and the Environmental Protection Agency (EPA), which, for years, has also cautioned pregnant women to limit their fish intake, announced that they are making changes to their fish consumption advice. The two agencies are now urging pregnant women, nursing mothers and those with young children to increase the amount of fish that they eat and feed to their children.

The revisions to earlier guidelines were made due to concerns that many pregnant women and nursing mothers do not eat sufficient amounts of fish based on the Dietary Guidelines for Americans 2010. An analysis of seafood consumption in the U.S. shows that over a fifth of pregnant women skipped eating fish in the past month and those who did ate fish had far less than the amount that would provide health benefits to them and their baby.

"We (the Food and Drug Administration and the Environmental Protection Agency) are issuing this advice to encourage women to eat recommended amounts and types of fish," the FDA and EPA said in a statement. "The nutritional value of fish is especially important during growth and development before birth, in early infancy for breastfed infants, and in childhood."

Studies show that fish contains nutrients that are beneficial to developing fetuses and young children. The docosahexaenoic acid (DHA), for instance is linked with healthy brain development while the eicosapentaenoic acid (EPA) is associated with good cardiovascular health. FDA's acting chief scientist Stephen Ostroff said that limiting fish intake during pregnancy and in early childhood could result in children missing out on nutrients that are crucial for their growth, development and overall health.

The new guidelines now advise pregnant women and breastfeeding mothers to consume at least 8 and up to 12 ounces or about two to three servings of a variety of fish that are low in mercury levels such as tilapia, catfish, cod and light canned tuna, per week and to avoid shark, swordfish, king mackerel and tilefish from the Gulf of Mexico as these are known to have the highest levels of mercury.