Unfortunately this kind of case only shows employers what potential 'problems' employing female pilots can pose. As far as I can see it, in her contract that she signed 4years ago, it would have been written down about how many hrs you need to go whatever% part-time. If she now wants to change that because she's had a sprog, well tough!
The standards should be the same for everyone. If some bloke had joined the company at the same time, had the same hours as her, and fancied going 50% to work as some volunteer helping sick people, it's pretty obvious he'd be shot down by the company as well. And in my opinion, that would be of same value to this world as bringing another child into it.
Rules are rules. If she doesn't like the fact that she can't go 50% at this moment in time, she should have either delayed her family-making or accepted it and taken a total career-break.
Oh, and I'm female!