Louise Mensch quit her job as a Conservative MP recently (http://www.bbc.co.uk/news/uk-politics-19146805). Her reason for the departure: to spend more time with her family (specifically her children). This is a common reason that women give when they decide to give up their careers. They want to spend more time with their children. Female doctors, lawyers, engineers, teachers, office bods all decide to quit their jobs to spend time doing something that is a) what they are biologically predisposed to do, b) less stressful and laborious than what they are currently doing.
So if looking after children is something that women are biologically inclined towards then what is the problem, why write a blog entry about it? Surely if the woman's happy, and the kids are happy, and their father is happy (that the kids are being raised by their own mother rather than a babysitter) then what's the problem, everyone's happy? Right? No, and to know why, read this article by Angry Harry; it's just bad economics to invest in something/one that is not going to give you a return on that investment:
Forcing employers to have 50% of their workforce as women is just bad business it's bad economics. That applies particularly ot high-skilled jobs such as doctors, surgeons etc where training takes five or more years.
If there are any plans to enforce '50-50' gender based employment quotas in your country, then write to your local political representative and tell them not to support it. If needs be, email them a short comment and a link to Angry Harry's article linked above. Anything is better than nothing.