Something's Fishy

Conflicting information about the safety of fish, especially regarding mercury, can leave pregnant women reeling. Here are the answers you'’ve been waiting for.

For years, doctors and nutritionists have touted the benefits of eating fish—it’s an excellent source of good-for-your-heart fats, lean protein and key nutrients. But recent reports of mercury contamination may leave you wondering if fish is still such a healthy catch for you and your developing baby. Mercury is a naturally occurring chemical from underwater volcanoes. It’s also an industrial pollutant that has been linked to developmental delays and learning difficulties in children. And while nearly all fish contain some mercury, large predatory species such as shark, swordfish, king mackerel and tilefish contain the most. As a result, the standard advice is that pregnant or breastfeeding women and small children should avoid eating “big” fish. A recent Harvard School of Public Health study found that children whose mothers eat large amounts of seafood high in mercury during pregnancy could suffer irreparable brain damage. New Environmental Protection Agency (EPA) data estimate that 630,000 babies in this country are born each year with high levels of mercury in their blood—more than double the previous estimate of 300,000 by the 1999–2000 National Health and Nutrition Examination Survey. The new estimate was based on recent research indicating that mercury in pregnant women tends to concentrate in umbilical-cord blood.

Putting findings into perspective Before you swear off fish altogether, some obstetricians and nutritionists argue that these findings do not necessarily reflect a danger for most moms-to-be in the United States. The Harvard study took place in Denmark’s Faroe Islands, whose residents consume very large amounts of fish and whale meat—not common practice in the States. A report from the Office of Environmental Health Hazard Assessment found that people in the United States eat an average of .35 to .6 ounces of fish a day, approximately one meal a week. As for the EPA estimates, exceeding the safety level does not necessarily mean a baby’s development will be impaired, since safe levels are set well below those known to show harm, says David Acheson, M.D., chief medical officer and director of Food Safety and Security at the U.S. Food and Drug Administration’s (FDA’s) Center for Applied Nutrition and Safety. Moreover, a recent study in the Lancet found no developmental defects in children born to women in the East African Seychelles islands, who ate an average of 12 fish meals a week while pregnant. And as for the increased mercury level in umbilical cord blood, experts claim that it doesn’t reflect the level in the fetus. “We don’t want to frighten people off of fish,” says Edith Hogan, R.D., a Washington-based nutrition consultant. “Fish is a good source of high-quality protein and is low in saturated fat and loaded with nutrients like iron, zinc and calcium.” And, species such as salmon and tuna are high in omega-3 fatty acids, which are critical for development of the baby’s brain and spinal cord. In addition, preliminary research suggests that a diet rich in omega-3 fatty acids may help decrease the chance of preterm birth.

The recommendations The FDA and EPA agree that pregnant and breastfeeding women should limit their fish consumption to two or three meals per week (not to exceed 12 ounces total); avoid mercury-harboring species such as shark, swordfish, king mackerel and tilefish; and limit intake of bottom-feeders such as clams and other shellfish. “Pregnant women should eat medium-size, commercially sold fish like salmon and flounder,” says Jonathan Scher, M.D., assistant clinical professor of obstetrics and gynecology at Mount Sinai Medical Center in New York. Check with your health department before eating fish caught in local rivers, lakes or streams to ensure that there are low levels of environmental toxins in the area. What about canned tuna? Hogan points out that the type used for canning comes from a smaller fish and doesn’t have the same mercury profile as fresh tuna. In fact, FDA tests show that canned light tuna has a lower mercury level than canned albacore. To be safe, don’t eat more than six ounces of albacore per week. The bottom line: To protect yourself and your baby, eat different species of fish rather than just one or a few types. Says Hogan, “As with everything else, variety and moderation are key.”