Why should welfare recipients be required to be on birth control?

I was reading an article on world of wealth where the ideas of birth control for those recieving governmet entitlements should have a IUD or get a vasectomy(men). I get the idea, but how well would that work. Wouldn't it be better to require them to join the military or marry someone with a wonderful income. Why is it always birth control? I am not against, just curious. Is it this bad?