New moms: Vary your workout for the best results. Try interval training by speeding up your pace for two minutes, then walking at a more moderate one for the next two, continuing the pattern throughout your walk.
Moms-to-be: Use a heart rate monitor to make sure you're not overdoing it, and judge how you feel on a 1- to-10 scale, 10 being the best. If you're not feeling great, slow down.
At the end of your walk, cool down at a slower pace for five minutes.