I was pleased that the NYT editorial board highlighted the recent study by John Santelli, Mark Orr, Laura Lindberg, and Daniela Diaz about decreased use of contraception in an analysis of the Youth Risk Behavior Survey. As the media reports it, Santelli and collaborators found that fewer teens are using contraception than previous highs a few years ago, and the speculation is that the decrease is from abstinence-only sex education.
Other research certainly indicates that abstinence is one plausible explanation for the decrease in contraceptive use. The trouble is that there are many other possible explanations, but the trend data on teen sexual decisions is so poor that we'll never know which explanation is responsible for this particular decrease in contraception use. The survey used by Santelli has at most a dozen relevant questions, and any information beyond that gets lost to the mists of time.
Some teens get pregnant because they want to. It's not a question of not knowing how to use birth control; they want someone to love them or to establish themselves as adults. Other teens get pregnant because they are in coercive relationships with older men who support them financially --- perhaps especially relevant in insecure economic times --- and the men want babies. I heard a story from a Maryland public school teacher about a 14 year old girl in her class who recently got pregnant because her 20+ year old boyfriend and his mother wanted her to; the boyfriend's mother wants to take care of the baby and the girl's mother is indifferent to the situation.
These stories represent more fundamental social problems than simply inconsistent or incorrect condom use, but the current data is so poor that if one reason for the lower contraceptive use was that more girls are being coerced by older partners to get pregnant, we would have no way of knowing. Such issues of teen pregnancy are not liberal or conservative, but some conservatives are opposed to funding surveys that would collect data to better understand the issues because they are uneasy about asking questions about sex to teenagers. If they could better understand the implications of their opposition, and what a good investment it would be to understand teen pregnancy better by funding an annual survey that monitors issues exclusively relevant to teen pregnancy and STD prevention, perhaps we could start to decrease the rate of teen pregnancy.