Speculating on Why U.S. Teenage Pregnancy Rates Are at Historic Lows

The Centers for Disease Control issued a new report which finds that the rate of teen pregnancy in the U.S. has fallen to the lowest level since 1946. In 1946 most teen moms got married. Of course, increased availability of contraception is likely to have had something to do with this decline. And for some reason, fewer teens are actually having sex. The crappy economy also likely contributes to this trend. In any case, see the CDC chart below.

Could it also be that the post-welfare reform trends identified in the chart from the Center for Budget Priorities and Policy below might be having some effect as well? 

Just wondering.