I agree with Thomcat - I personally have never had a problem with working f/t and choose not to feel any guilt.
I went back to work when ds was 4 months old (he's now 5, so it was when maternity leave was only 4 months). I love my ds, but never felt any guilt, as I knew he was happy in at the childminder's, who was the house next door.
He only stopped going there last week, as he started full days at school (plus after school club) this week (for the past year he was been going half days - mornings at nursery and then since August at school). He has been happy there the entire time - runs in smiling, sometimes needing to be reminded to say good bye - and, just as importantly, running out smiling, with a biiiig hug for his mum or dad (whichever of us picked him up).
For the first few years of his life, both dh and I worked full time - and neither of us had any problem with that, even though we could have "afforded" to have one of us stop. For our perspectives , and the character of our son, we knew we were doing the right thing for us. And no, we don't think we missed out.
We both still loved the early mornings and the evenings from 5.30 when we picked him up, to 8 when we put him to bed. I even continued to breastfeed him till he was 13 months old, expressing at work.
As it happens, dh took a package about 3 years ago - but has used the time since to explore various other options and is currently studying (near enough full time) to be a Master of Wine. We never even considered taking ds out of the childminder's - although dh's flexibility did mean that if it were a really nice day, he could go and get ds and take him to the swing park, for example.
The one thing I have missed is "me" time: my dream has been to drop a day (or three days over two weeks), so that I have some time for myself. If I'd been able to do it before ds started school, I wouldn't even have reduced the childminder's hours - as that day would have been for me. Now some weeks, I might have chosen to take him out and go and do something together - but other weeks, I would just have used the time to relax, see friends, whatever.
Selfish? Perhaps. But ds is a loved, happy wee boy and I don't think he has missed out on anything.
Even though ds has now started school, I still dream of being able to reduce my hours - but will probably need to wait until dh starts earning again. One day it will happen .
I suppose what all that rambling comes to is while I can understand that some mothers/people can say that they don't understand how other mothers can choose to leave their children and work full time, as they themselves couldn't, I don't understand how they can judge or apparently condemn mothers who choose to do so. What is "right" for them is not necessarily right for others.
I am not a natural "earth" mother - and would go doolally if I were at home all day. I am however, still a good mother!