The first thing I would recommend is listening to your body and consulting with a doctor. I would make sure you have sufficiently given your body time to recover from labor. This may take anywhere from 6 to 8 weeks. For some it may be sooner or later, everybody is different. It is better to take the time to recover than risk injury to yourself that may result in more time off of exercising. During your visits with your doctor in this time frame, let the doctor know how you are feeling and consult with them about returning to a fitness program.