At 20 weeks I also noticed a tingling and numbness on my upper left thigh. If on my feet an hour or more, it begins feeling cool, then turns to a burning sensation (sometimes almost unbearable). At my most recent check-up, my doctor explained it is a pinched nerve, due to my growing uterus. She said it is fairly common, nothing to worry about, and should go away shortly after delivery. I hope this helps!View Thread