This is what happens when you teach kids that condoms don't work

AP (emphasis mine):

About 17 percent of sexually experienced teen girls say they had used the rhythm method –timing their sex to avoid fertile days to prevent getting pregnant. That\’s up from 11 percent in 2002.

They may have been using another form of birth control at the same time. But the increase is considered worrisome because the rhythm method doesn\’t work about 25 percent of the time, said Joyce Abma, the report\’s lead author. She\’s a social scientist at the CDC\’s National Center for Health Statistics.

…

The increase in the rhythm method may be part of the explanation for recent trends in the teen birth rate. The teen birth rate declined steadily from 1991 through 2005, but rose from 2005 to 2007. It dropped again in 2008, by 2 percent, to about 10 percent of all births.

In related news, more high school soccer players are using cardboard for shin guards.