Sorry, I've been behind on threads and just now saw this. My personal experience is not with women looking for state/federal benefits (which, like in the UK, is not much money at all,) but rather those aiming to get child support payments from the father, which are on a sliding scale with his income and have no upper limit. Get pregnant by someone with a $100,000 per year income, and you've got yourself as much as $30,000 a year for the next 18 years. Repeat as necessary for each different father. As an offhand count right now, I can think of... at least 5 women who either deliberately got pregnant (with additional children, not their first,) or kept babies they otherwise would have aborted if the dads had been brutally poor, because they wanted the child support money.

I was on the other side of that. Clods right on as usual.
Unfortunately there are plenty who do it for the gov't money as well.