Experts have long debated what levels are hazardous. But last summer the National Academy of Sciences concluded that mercury from food could be putting 60,000 babies a year in the United States at risk for problems including delays in talking and impaired fine-motor skills. It's not like a broken leg. To lower the risk, eliminate the four types of fish as soon as possible if you plan to become pregnant and avoid them until after you've finished nursing. Yet don't panic if you ate swordfish the week before you found you were pregnant.
Some experts believe it takes consistently high levels of mercury to cause neurological damage.
And pregnant women don't need to forgo all fish. According to the FDA, they can safely eat up to 12 ounces a week of any cooked fish other than the four on the list. The listeria warning, too, has been a long time coming. But it can lead to meningitis and blood infections in babies, children, and people with weakened immune systems, resulting in an estimated 500 deaths in the United States each year. Pregnant women are 20 times more susceptible to the infection, and when it crosses the placenta, it can trigger a miscarriage or stillbirth.