Why can't pregnant women eat crab?

Mercury: Crabs and other shellfish are scavengers. They tend to eat dead fish that drop to the bottom. The fish that died had acquired a lifetime of heavy metals and is now eaten by the shellfish. This tends to concentrate heavy metals in the shellfish. The most worrisome heavy metal is Mercury. For this reason, it is recommended that you limit your intake during pregnancy. Best wishes!

The new FDA and EPA: guidelines published in 2014 say it is ok. Scavengers like crab and lobtster actually have low levels.Only the predators at the top of the fish-eat-fish food chain concentrate methyl-mercury (from our coal-burning power plants) to dangerous levels. Recent data is best, as we continue to contaminate. Several have a max/wk. http://www.fda.gov/Food/FoodborneIllnessContaminants/Metals/ucm393070.htm