For years the FDA has warned pregnant women about mercury, the defect-causing pollutant that builds up in fish--and the women have responded. Last Thursday, a survey reported that expectant mothers have eaten 1.4 fewer servings of fish per month since the FDA launched its anti-mercury campaign. But on the same day, a Stanford study revealed that the mercury found in fish is not methyl-mercury chloride--the kind known to damage fetal nervous systems--but another form that might be less toxic to humans. Then again, it "might be more toxic," says biophysicist Graham George. Why the confusion? Scientists just don't know how mercury compounds break down in the human body. That's George's next step, though, so stay tuned. You should probably continue to avoid swordfish and mackerel until the experts get their fish story straight.