I stopped eating steak when I was pregnant because I like mine rare. Not sure why, but it took me 14 years to eat steak again.
Unrelated to pregnancy, but I used to love popcorn. The movie theaters smelled so good to me. One summer about 10 years ago the smell of buttered popcorn made me nauseated and I completely stopped eating it. Couldn't even stand the smell of it in the theaters or the work breakroom. Never have gotten over that smell.