...I believe. If the immediate disincentives to teen pregnancy (shame, ostracization, removal from the marriage market, etc) are removed, and in large measure they have been, then providing some incentives to do the "right thing" may do the trick.
The incentive is really being paid for the girls to be active in a program that is providing them a lot of information on how and why to avoid pregnancy...not having a baby is probably more a result of that than the $1 a day. It's a way to take girls who are at high risk (read the criteria for participation) and get them to commit to talk and think about the issues around teen parenthood. If the price of a number one meal or two at McDonald's a week helps them stick it out, great.
Plus, we incentivize good grades, coming home before curfew, and other good behaviors with our kids all the time. Just because it's not always money doesn't make it any less an incentive.
I don't have a problem with it.