psammead It's all a bit unfair when young, working class pregnant women are seen as society's scum, whereas slightly older, middle class preggos are people to be respected and pampered I agree. I think it's more than that though, people assume that middle class teens don't get pregnant. They do, it's just a lot less obvious.
My mother's neighbours daughter is one such case but her parents built an annexe for her and the baby to live in - so she's not on the housing waiting list. She isn't attending parenting classes and she isn't committing any of the MN parenting faux pas because she had a good upbringing herself, she just became pregnant in her teens. I think her child is about 7 now and they still live there. She also has another child and is still living there on her own. It's less obvious because she and the children are dressed nicely, she doesn't draw attention to herself because of her conduct and to any passerby she looks like a lovely young mum out with her delightful children. I don't know if she works, her sister went to university.
People worry about young (and lets be fair it's not the 'working class' people are bothered about it's the 'benefit class') unemployed, uneducated mothers because they hand wring and worry about an epidemic, they worry about the cost to the state, they worry they will 'breed' (to use a MW favourite!) every year between now and the menopause. They worry about the pressure on the state of any children those children will have in terms of the additional 'interventions' a lot of these families require.
lastnerve is right, there are an incredible number of dysfunctional middle class families but due to 'keeping up appearances' they are less obvious because their lives tend to play out less publicly - they want to be seen as decent and respectable by their neighbours and by the school so it all happens behind closed doors.