This just in from Harvard University: In an ongoing study of 341 mother-child pairs, women who ate the most fish during their pregnancies had children with the highest cognitive development scores at age 3. Read that sentence again. April Fool’s day isn’t until next Monday. And women who ate two or more servings of canned tuna every week while pregnant had smarter babies than those who ate none. Again, we’re not joking.

This important study, set for publication next week in the American Journal of Epidemiology, is just the latest sign that activist groups like Oceana, the Environmental Working Group, and the Sea Turtle Restoration Project are dead wrong about the supposed health threat from trace levels of mercury in fish.

“The 28 mothers (8 percent) who reported eating canned tuna at least twice weekly had children with higher scores … compared with the 130 mothers (38 percent) who reported never eating tuna fish” while pregnant.

Science is rarely this clear-cut, and this report is no exception. Mothers who ate more fish naturally had higher mercury levels, and the highest maternal mercury levels were associated with slightly lower children’s test scores. But the devil is in the details (and no one ingests mercury without also getting fish-related health benefits). When researchers examined the combined impact of these health benefits along with mothers’ mercury levels, something remarkable emerged:

“We next examined maternal fish intake and mercury levels simultaneously … Children whose mothers consumed more than two weekly fish servings and whose mercury levels were in the top decile also had somewhat higher scores, whereas children of mothers who consumed up to two weekly servings of fish and had mercury levels in the top decile had somewhat lower scores.” [emphasis added]

Translation: Among mothers with the highest mercury levels, those who ate the most fish (more than two servings per week) had children who performed above average on cognitive tests. High-mercury moms who ate less fish were the ones whose kids appear to be at a disadvantage. The key appears to be tuna. The most maligned fish in the sea, it turns out, is actually a comparatively low-mercury choice. We found as much in our 2006 fish-testing reports (see page 7 here, and page 10 here).

Don’t take our word for it. Dr. Oken told London’s Independent newspaper on Sunday that “women who ate more than two weekly servings of tuna had children who performed better on the developmental tests.”

Her research team has previously found that “fish intake among pregnant women declined following the 2001 federal mercury warnings” issued by the Environmental Protection Agency and the Food and Drug Administration. Time will tell, but it may be that government warnings are contributing to a generation of fish-fearing moms whose kids are needlessly underdeveloped mentally.

Today we’re telling the media that “at a time when environmental activists are branding fish with a skull and crossbones, this is helpful evidence that fish is still the same health food it’s always been … women who run away from the fish counter during their pregnancies are clearly putting their babies’ health at risk.”

“Science doesn’t lie. Pregnant women who frequently eat canned tuna are having brainier children than those who don’t. Green groups have been demonizing tuna for years. Now it looks like they’ve been causing the very harm they sought to prevent.”