Like HerBex said earlier, most people (male and female) don't have careers, they have jobs. Most people (male and female) can request flexible working to a degree, but that isn't going to equate to being able to pick and choose their hours.
Most people (male and female) are not higher rate tax payers, so saying all women need to make better career choices when at school/college/uni/taking their first job is a very ineffective solution to women achieving more equality in the workplace. There simply aren't that many top jobs to go round full stop. If every 16-year-old girl alive today did this and became a lawyer/doctor/banker (whatever) in the future all that would happen is that salaries in that sector would decrease, meaning they would be no better off than any woman working today in an ordinary job on an ordinary salary. The nature of capitalism requires the top earners of our society (male or female) to be a minority.
Having children is not something that is going to stop happening. It is the driving force behind the continuation of our species. It's not a lifestyle choice in the same was choosing to give up a car.
Someone - usually a woman - has to care for and rear these children to independence. This is a issue that affects the whole of society, since the vast majority of us are parents, yet the cost is borne disproportionately by female parents.
Many many women wish to care for their children themselves, while others have no choice but to do that themselves because childcare costs are prohibitive to anyone on an average salary or less.
We have to recognise that our society fundamentally requires childbearing and rearing to continue as much as it does economic growth. One cannot exist without the other. Yet one is held in much higher regard than the other, in a way that disproportionately favours men.