Pregnant women should eat at least 8 ounces of fish each week, which puts a floor — not just a ceiling — on the amount of seafood these women should consume, the FDA and the Environmental Protection Agency (EPA) announced in a draft guidance.

The recommendation, which translates to two to three servings of low-mercury fish per week, is consistent with those in the 2010 Dietary Guidelines and also applies to breastfeeding women and those who might become pregnant.

Both agencies also advised that young children get two to three weekly servings of fish in proportions appropriate to their age and caloric needs.

The recommendation breaks from the earlier 2004 guidance which only put a cap on fish intake. FDA acting chief scientist Stephen Ostroff, MD, said during a press briefing that the agency’s review of the science now suggests a floor on intake given the neurodevelopmental benefits of fish — particularly its ability to improve IQ.

Both agencies recommend selecting fish proven to be low in mercury content, including shrimp, pollock, salmon, canned light tuna, tilapia, catfish, and cod. Ostroff said these account for the majority of the most commonly consumed fish in the U.S.

Only four fish are on the do-not-eat list in the current update: tilefish from the Gulf of Mexico, shark, swordfish, and king mackerel. Ostroff noted that these account for “less than 2% of all market share in the U.S.”

But during the briefing, EPA’s director of science and technology Elizabeth Southerland said the agency will ask during the comment period whether orange roughy and marlin should be added to that list.

FDA and EPA also advised that women should limit their intake of albacore tuna — whether in canned form or as steaks — to 6 ounces a week, given its higher mercury content.

Fish caught in local waters should also be limited to 6 ounces per week for adults — and 1 to 3 ounces for children — because the watershed may not be monitored and it may not be possible to determine mercury levels, officials said.

Ostroff emphasized that most pregnant women in the U.S. aren’t eating enough fish, citing a recent survey that showed 50% ate less than 2 ounces per week and 75% consumed less than 4 ounces.

“A large proportion of pregnant women aren’t eating enough fish, and they’re missing out on the health and developmental benefits fish can provide,” he told reporters.

He also noted that fish oil supplements won’t suffice: “There are a variety of things found in fish, including proteins and other nutrients,” he said. “It isn’t simply the omega-3 fatty acids that should be focused on.”

The FDA’s risk communication advisory committee will hold a meeting on the draft guidance, and the comment period will be open until 30 days after the last transcript from its meeting is published.