Bob, Bob, Bob
I'm male and work with many women in my current role, some do work part time and invariably end up working more hours than paid for, re-arrange their hours around business priorities and often still have the responsibility for caring for young children or elderly relatives.
Whilst some women do decide to be stay at home mum's this is a very small minority in the UK today, most professional couples continue to need both incomes to keep their heads above water. What is more common now is the mum's who have to return to work before they are ready, working longer hours than contracted and feeling guilty about the impact this is having on their kids.
I'm in my 50's now and my first wife was able to take a few years out to look after our children until they were established at primary school. This was a joint decision as I'm sure it was between Bob's sister and her husband. By the time the kids were in school my-ex was desperate to return to her professional role but found breaking back into the jobs market incredibly difficult. In order to do so she took roles where her salary didn't even pay the child minders costs, we were very lucky that we could afford to do this. I suspect in cases where the mother wants to return to work but can only do so by taking a much junior role on a hugely reduced salary that won't pay for child care then some women are kept out of the professional job market and end up taking on lower paid work which can be scheduled around school and may never be lucky enough to re-enter their professions.
You'll have gathered that I am no longer with my ex wife, our divorce was long, bitter and personally very expensive but none of that relates to her work history, professional ability fitness as a mother or any other characteristic.