Go read Emily's post at After Abortion. She covers all the facts.
After I read this, I realized why the New York Times suddenly published that article saying that parental involvement laws had little impact on teen abortion rates: They wanted to fire a shot to sink a New England Journal of Medicine article revealing that parental involvement laws cause teen pregnancy rates to fall around 25%. This information, of course, would lead voters to support parental involvement laws. Since that's not part of the abortion orthodoxy, the Times, in order to be effective propagandists, had to establish as "common knowledge" that parental involvement laws have little impact. This move would allow the NEJM article -- which propagandists would hope would be read only by a limited audience -- to sail right past without voters absorbing the facts.
Ironic that this played out while I'm in the middle of re-reading Jacques Ellus's excellent Propaganda: The Formation of Men's Attitudes.