Except, when you read the Reuters article you have this:
The researchers did not evaluate the content of sex education programs, including whether students were taught about contraception or about abstinence only.
Huh? Either Reuters is misreporting or the quality of research at the CDC is seriously lacking.
If you don't know whether the programs you're evaluating do, in fact, teach sex ed (comprehensive programs), or not (abstinence-only programs), you can't draw any valid conclusions about the effects of formal sex education on the timing of teenagers' sexual debut.
For all you know, most, or even all, of the programs you evaluated were abstinence-only programs, in which case the finding, and the headline, would be "Lack of sex education found to help teenagers delay sex."
If you have access to the study, please share; it would be interesting to find out who the clueless culprit is, Reuters or the CDC.
UPDATE: Here's the abstract, thanks to reader lyrl.