The black teenage birthrate has fallen sharply since the annus horribilis of 1991. Back at the peak of the Crack Era, 86 of every 1000 black girls from 15 to 17 gave birth, versus only 32 in 2009:
It's important, however, to note that the 1991 number represented a spike in teen fertility among blacks, up over the 1980s and well above the late 1990s. Nobody seems to know why that happened. One guess is that black girls in 1991 found crack dealers sexy, but changed their minds rather quickly. Another is that the FDA's approval of the Depo-Provera shot in 1992 was the turning point. The welfare cutbacks of the mid-1990s certainly played a role.
Among 18-19 year olds, the fall hasn't been quite as steep:
The subprime bubble of the middle of the last decade appears to have inflated Hispanic teen fertility -- thus the sharp drop among Hispanics from 2007 to 2009.
Nobody these days seems to know anything about fertility trends, although it's hard to think of anything more important.