Why do people stare at a pregnant woman?!

So...i am catching up with a good friend of mine. I am in the pub with him, NOT drinking of course but people keep looking at me like i am doing something wrong! I am too scared to go to the bar to buy my friend a drink because the barman already made a comment to my friend about how "i hope your young lady friend isn't drinking because i could get the sack" I feel like i need to wear a sign saying "Don't worry i am not drinking alcohol! I am just trying to enjoy my friendships before my little one comes along and i am not out at 11pm for some time! Grrrr!