Well, subman, if you are interested in birth rate research, take a look here:
http://en.wikipedia.org/wiki/List_of..._by_birth_rate
the USA rate is remarkably close to that of the UK (only two more births per 1000), which is only to be expected as most developed nations tend to have low birth rates.
I'm not really sure about what point you are trying to make in your post - perhaps you could explain your arguments a little. For example, you seem to consider 'liberal' attitudes to marriage a bad thing - could you explain why?
How about your personal feelings? Do you see marriage as a good or bad thing, for instance?
Personally, I would love to see the population of the UK decline, although there is no actual sign of that. I would finally find somewhere to park...