@Oakenbeach
YANBU. I don't get it either. Maybe I am just old fashioned, but no way in hell would I have children with a man if we weren't married.
Women are putting themselves into a very vulnerable position by having babies without being married.
I am sure a bunch of posters will come on telling me I am talking shit, and they earn WAY more than their partners and are not even remotely vulnerable. But the fact is that most women are/will be.
What you have to ask, if your man will not marry you, is WHY not? Also he is sending a message to your children, that their mother is not good enough to marry.
I think women who stay with a man and have kids with a man who refuses to get married, must have low esteem. I am sure there are a few women who are content to stay unmarried and insecure and vulnerable, but they are in a minority. I mean why would you, seriously? 
And the 'we can't afford it' line has gotten old. ANYone can afford to get married. It cost pennies. That's an excuse (usually perpetuated by men who don't want to get married!) Men spend vast sums on their 'man hobbies' like golf and fishing and footie (like multiple 1000s a year sometimes,) but say 'we can't afford to get married.'
Don't be a mug lady! If he wants to marry you, he will, no matter what!
And yep, a 'common law wife' is a myth. It doesn't exist, you have no rights than flatmates, and you have less of a say in ANYthing than his siblings and parents. In fact his cousins, aunts, and uncles probably have more rights and say in legal things than you. That includes any inheritances or the right to switch off (or leave on) your partner's life support.