Hi! When I was pregnant with first (early 2010), the hospital offered classes.. They were cheaper than most yoga studios, you can get the info. from your OBGYN if they deliver at Abington.
I just had a baby in october :-) I taught PreNatal all through my pregnancy and it really helped me. I am back to teaching in Elkins Park (2 towns over) at Shakti Yoga. www.shaktiwest.com . $15 drop in but class card discounts available.