Experts Discuss Pros and Cons of Fish during Pregnancy

Women who are pregnant should include fish in their diet for optimal maternal health and fetal growth and development. That much health experts agree on.

But just how much fish moms-to-be can safely consume without exposing their unborn babies to dangerous levels of mercury is a matter of ongoing debate.

The US Food and Drug Administration (FDA) advises women to eat no more than 12 ounces a week, but a coalition of scientists in nutrition and medicine insists that expectant moms need at least that much or more.

"Recent data shows us that women are still not eating enough fish, and that's really alarming," says Judy Meehan, executive director of the National Healthy Mothers, Healthy Babies Coalition, an organization dedicated to disseminating the latest science on maternal and child health.

"There's simply no other way to get the omega-3s for brain development that you can from fish," she says.

High Omega-3, Low Mercury is Best

Fish is packed with omega-3 fatty acids, a beneficial type of fat that is considered important for neural development.

Limiting fish intake to the government-recommended level, in fact, could be "detrimental" to a child's mental development, British and American researchers reported in 2007 in The Lancet.

Their study found that children whose mothers ate at least three servings of fish a week during pregnancy performed better on tests of mental function.

In another study, Dr. Emily Oken, at Harvard Medical School, examined the balance between the nutritional benefit and contaminant risk of consuming fish during pregnancy.

She and her colleagues asked 341 women about their fish consumption during the second trimester of pregnancy and tested their blood levels for mercury.

When their children were three, they took a battery of tests to assess intelligence and motor skills.

"Test scores were highest in children of mothers who ate more than two weekly fish servings but had lower mercury levels, suggesting that the greatest benefit occurred when women ate fish low in mercury," says Dr. Oken.

"Even mothers who ate canned tuna more than twice weekly had children who scored better on tests, compared with those who did not eat canned tuna during pregnancy," she adds.

Another study looked at over 25,000 children born to Danish mothers. Kids whose moms ate more fish during pregnancy had better motor and cognitive test scores than those whose moms ate the least amount.

"Compared with women who ate the least fish during pregnancy, women who at the most fish - about 14 ounces per week, on average - had about a 30 percent likelihood of better development, about the same advantage a child would get from being one month older or from breast-feeding for more than one year," explains Dr. Oken.

Two Servings Per Week

In 2007, the National Healthy Mothers, Healthy Babies Coalition partnered with the Maternal Nutrition Group, an independent group of physicians, researchers and nutritionists, to encourage pregnant women to eat fish as part of a healthy diet. The concern was that many women were interpreting the FDA guidelines as a warning and curtailing their fish intake.

The FDA advisory, first issued in 2004, targets women who are pregnant or may become pregnant as well as nursing mothers and young children.

These populations are urged to avoid certain types of fish that may be higher in mercury and therefore toxic to a baby's or child's developing nervous system. These include shark, swordfish, king mackerel, and tilefish.

The FDA recommends choosing varieties lower in mercury and eating no more than 12 ounces - or roughly two meals - of fish a week. The total amount should include no more than 6 ounces of albacore tuna a week.

The American College of Obstetricians and Gynecologists echoes that advice in its own nutritional guidance.

Still, many Americans, including expectant moms, do not get at least two servings a week.

"The message is, eliminating fish is not a good thing," says Meehan. "Fish is uniquely important for brain development in babies."

Always consult your physician for more information.