I've already been flamed once on this supposedly conservative forum for pointing out the stupidity of actively rewarding such behavior. I'm not sure if it's because "conservatives" don't think that getting knocked up at 17 is irresponsible, or because they think that personal irresponsibility should be subsidized in general.
Might I suggest a different way of looking at the situation? Perhaps the problem isn't the fact that people want to have sex (and get pregnant) as teenagers. Especially since nature seems to have designed human beings to do just that, and since medical research into the subject indicates that people who delay childbearing experience more problems with childbearing the longer they delay it.
Perhaps the real problem is that we have created a society where people have to work so hard for so little that they feel they cannot responsibly afford children until they are almost too old to have them, and their fertility has fallen almost completely off the charts? Perhaps the real problem is that the average guy cannot make enough money to afford to provide for a wife and children until he is well into his thirties, if then?
To summarize, I submit that this problem is really a problem of government policy and economics rather than one of "values" or "responsibility", and is because our society has agreed to lock itself into a suicidal paradigm.
The difference is, the pregnancy isn’t the bad behavior. The extra/premarital sex was. Once a girl is pregnant, I don’t see the point in “punishing” her. I don’t want her to abort the baby to hide things.