I liked this article, and added my own the on it that you can also incorporate your baby onto your workouts at home.
Situps with your baby between your feet
Squats with your baby in your arms
Bench press motion with your baby, they love that up & down motion, with your face appearing in focus (like the Situps earlier)
Sprints with your buggy (esp up hills)
Just have a think… Why go to the gym when you can involve your new baby!