A couple years ago, I graduated with an undergrad degree that really did not get me very far in terms of job prospects. I was living with my boyfriend's parents and I was working an internship. Nobody has very much sympathy for a twenty-something mooch. It's not easy to become financially independent without a lot of support, even past the point where people feel like supporting you, but I was trying my best to work my way up. And then I got pregnant. Suddenly I had parents, in-laws and distant relatives coming out of the woodwork to throw money and gifts at me. Suddenly I was buying a house and people were offering to supplement my heating bills because God forbid the baby freeze.
My son was the first grandchild on both sides, so this get-rich-quick scheme might not work for people with bigger or younger families, and I am not at all saying that this is a reason for someone to get pregnant, but it is certainly a huge perk.