I would only be guessing why that population is growing as fast as it is. Over the last 10 years, the women offender population has grown by 9% per year on average. Between 2006 and 2010, the women offender population increased by 23%. In fact, it increased by 28% for aboriginal women.
Everyone has been taken by surprise by this trend. It's very complex and sad. I would only be guessing about the social context and environment that might be contributing to making them more vulnerable to being criminalized. The criminal justice system ends up taking care of folks who probably also need a lot of care from social and mental health services.