I'd say something like, "i asked my doctor and he says it's ok."
I'm guessing this is your first, or it's been a while between kids, but get used to it. People, especially those without kids, feel the need to tell you what to do. UA will follow you. Don't dare let her eat hot dogs, seafood, wine, lunch meat, etc in public. Oh and wait until the baby is born!! I still get the stink eye while out with my 3yr old and 18month old because i'm doing x, y or z. Best advice is ignore them and move on or you'll be one pissed off mo fo.
Good luck and congrats!!!