Scientists in the US have recommended that pregnant women and nursing mothers eat more fish to ensure optimal brain development in their babies.

They should eat at least 12 ounces (about 340 grams) of fish per week or about two servings per week, the scientists said.

Conventional wisdom is that eating seafood may harm newborns and foetuses because many marine species contain high levels of mercury. Many pregnant and nursing women avoid seafood altogether.

But the scientific advisors of the National Healthy Mothers, Healthy Babies Coalition, a non-profit group, say that eating 12 ounces was very safe, reported the online edition of The New York Times.

Judy Meehan, executive director of the group, said: “The real problem here are the women who are just eliminating fish from their diet.”

For women who want the health benefits but worry about mercury and other toxins, the wisest course is to choose fish with the lowest levels of mercury, the scientists said.

An increasing number of studies have indicated that omega-3 fatty acids, found mostly in fish, are essential for brain development in foetuses and newborns.

Earlier this year, a report published in the medical journal The Lancet concluded that women who ate over 12 ounces of fish per week during pregnancy had better developed and more intelligent children.

Health benefits are likely greatest from oily fish such as salmon, herring and sardines — which are all generally low in mercury. Among the fish to avoid are shark, swordfish, king mackerel and tilefish, which may contain high levels of mercury.