A book called "Cycle Savvy: The Smart Teen's Guide to the Mysteries of Her Body" is causing a stir in the old "how much should we tell teenagers about sex" debate. In it, Toni Weschler (author of the 1995 hit "Taking Charge of Your Fertility," aimed toward older women) presents young women with information about their periods (including why they happen, what might cause PMS, and how you can chart your fertility cycle to better get to know your body).

According to the Washington Post, this last part is the controversial bit -- because while fertility charting can give you a whole lot of non-sex-related information about your body, it can also be used as a method of birth control.

Let's make one thing clear: We're not talking about the rhythm method. Fertility charting, when done correctly, is only slightly less effective than oral contraceptives (or so said a recent report in the journal Human Reproduction). But doing it correctly takes a lot more effort than slipping on a condom (or, for that matter, popping a pill). You need to do things like monitor your body temperature daily, keep track of the position of your cervix and, you know, check out the consistency of your cervical mucus.

In other words, it requires a hell of a lot of attention to detail -- which is why I don't understand why people are so concerned that teenagers will pick up this book, give it a quick skim, and decide that it gives the go-ahead to have tons of unprotected sex. In fact, according to the Post, the book doesn't even go into detail about how to use fertility charting as a form of birth control -- after winning a debate with her co-author (who happens to be her brother), Weschler suggests that fertility charting can be used as a form of birth control but, as the Post puts it, "says that this should only be done by adults and stresses that adolescents should never have unprotected sex." It also helps women tell the days on which they're most likely to become pregnant, but doesn't stress the opposite (i.e., the days on which they're least likely to conceive).

Personally, I've never bought the argument that if you give teenagers more information they're going to run out and have more sex. I'd instead suggest that any girl who's going to devote time to taking her temperature and checking out the daily position of her cervix is not the girl we need to be worrying about. We need to be worrying about keeping the "mysteries" of the female body so mysterious that young women end up accidentally pregnant.