I work in a termination service. (i have changed my name)
I have not yet met a girl/woman who is not deeply upset by having a termination. Just about all of them cry or well up, and expect to be shouted at for being naughty (when of course we do not shout, we are sympathetic).
1 in 3 women under 45 in the UK has had a termination at some point in their life.
The reason (as I understand it) for the dropping of termination to 24 weeks is that somewhere between 22-24 weeks babies lungs mature. Before that point there is very little point in debating about the fetus - it could not survive. by 24 weeks, almost all babies have developed lungs. (this is why you have steroid injections if you have a threatened early labour).
I do not enjoy my work, I see it as helpign women in a difficult situation, and I consider it my primary function to get them on effective contraception, either before the termination or asap after.
in Holland anyone can get an abortion up to 12 weeks without seeing a dr.
And as to 'when do you know' it is very difficult for young girls with irregular periods, who may not want to 'acknowledge' the problem. I have seen several 15 yr olds who tell me they are 8 weeks, and when i examine them they are 16 weeks or so - their faces make me believe they suspected as much, but just didn't want to face it.
Abortion should be legal safe and rare, in my opinion.