I dont eat seafood, but if I did, I dont think I would eat it cold. I would heat up the prawns before eating them just to be on the safer side. I've eaten ham during my pregnancy, but I've heated it up and eaten it hot. I read somewhere that you dont always get symptoms if you get listeria, so you might not know if you have it, and since our immune systems are lower during pregnancy, I am trying to be 'safe' with the food I eat.