I think there's much to be said for discussing these issues with one's partner before embarking on children, or at the very least during pregnancy. I know people say 'you won't know how you feel until the baby arrives,' but it's not a bad idea to strike a balance between the discussions you have pre-children, and the emotions after the baby arrives.
From my own experience, when we had dc1, giving up work wasn't an option financially. Therefore no matter what emotions I might have had when dd arrived, we simply had to find childcare and I had to return to work, albeit only 3 days a week, when dd was 12 weeks old.
And here's the thing: if I had had a choice, who knows? - I suspect I may have given up work, because returning with a 12 week old bf baby was physically very demanding.
However, returning to work was the best thing I ever did. I proved to myself that I could do it; that dd was fine and I was keeping my hand in (albeit that the phase of 3 day working was more career maintenance than career building. )
I suspect if I'd stopped working, my confidence levels might have dropped and it would have become progressively harder to re enter the workplace. Not because of any inherent 'unfairness', but simply because in the workplace, particularly when it comes to the higher status more interesting roles, you're always going to be competing against men and women who havent had time out.
By the time dc2 and 3 arrived, financially I could have stopped working, but chose to continue (despite my salary only covering childcare for several years, so no immediate financial gain) because I knew first hand by then the advantages of keeping that foothold. The other thing that worked well for me was to step back up to f/t as soon as my youngest turned 4. This was the best way to get my career moving forward again; not because it's impossible In a p/t role, but because if you're willing to work f/t too, you're inevitably going to make yourself attractive to a wider market. I have many friends in similar roles to me who chose to stay working 3 or 4 days a week pretty much permanently, all through their children growing up. Nothing wrong with that, but inevitably there are downsides such as not having a great pension pot, and not always having the career options which they'd have if they were prepared to work f/t. It's a trade off isn't it? - if you are choosing to work p/t presumably you weigh up the pros and cons and do what you feel is best for your family
The absolutely must important factor I believe is to choose a partner who will work as a team. If I'd partnered someone who believed his career was superior to mine, and who expected me to always play second fiddle and mop up all the domestic side of things, then quite frankly I would be reaping what I'd sown.