I started laughing reading this one and the last response (I'm a new mom too and ya...we do tend go on!!), so I thought I should at least add my two bits!
Have worked with people in a return to work setting (mostly men...the difference is they talked about hunting instead of babies) and had some of the same issues.
My advise would be to be creative with exercises as noted in the last response. Do the typical "physio exercises" but add in elements of pilates, yoga etc. Lots of education too - get them talking about something else. And probably the most important (as far as I'm concerned) is goal setting. Make them accountable for their progress. Make them aware of what they are doing and why. In almost every group, there is usually at least one person that will switch from moaning to encouraging & motivating not only themselves but the people around them (yes, even women!!!).