S.H.
E., this isn't near downtown but may have what you want. Galter Life Center at 5157 N. Francisco has waterobics and various yoga classes + classes for babies and toddlers. I attend a chair yoga class, and at least one participant comes from Hyde Park as she feels it's worth the trip. Check them out at
galterlifecenter.org
Good luck and congrats on the new baby.
S.