Pregnant teens are an easy target, because they have obviously done something wrong. They are also not regular voters, which makes them a more likely target than the elderly, who vote regularly. I deplore the moral standards which wink at and reward those who lack the self control to wait until an acceptable time, but I don't relish the thought of punishing them by starving their babies. Welfare is actually a name used to describe many different programs which all do roughly the same thing - give money to poor people. Some of them used to try to do more, but increasing government regulation and restrictions make it harder to do anything but give away money freely.
Welfare fraud is rampant and examples of abuses are plentiful.
The sad part is that the purpose of welfare is an honorable one, and we should indeed be helping those less fortunate than us. With the government involved, however, we aren't actually helping, we're having money taken away from us. The fraud and abuses only hurt the people who need the money the most. In a perfect world, there would never have been any entitlement programs. Everybody would save some out of their income for their retirement, knowing that the day would come when they had no income.