Counterintuitive Science - Abstinence Doesn't Reduce Pregnancies

This is one of earliest counterintuitive results that I learnt about.

Many years ago, I walked past a booth set up by eager undergrads at the Students' Union Building at my university.

It was an information booth promoting the awareness of the HIV/AIDS and encouraging safe sex practices.

One of the colourful billboards contained a table about pregnancy rates corresponding to different birth control methods.

I don't remember the exact percentages now, but it said that condoms are over 90% effective at preventing pregnancy, while abstinence is ... over 80% effective.

Eh?

Not 100% effective?!??

How can NOT having sex have a higher chance of producing babies than actually having sex?

I asked one of the volunteers at the booth, and she explained that the main reason for this is that people claim that they'll abstain, but go ahead and have sex anyway - except they do it without any protection.

The result is completely opposite to what common sense would predict.

In addition, recent studies have shown that advocating abstinence has no effect on the sexual activity of teenagers, and more worrying, doesn't increase the rate of condom use.

This is dangerous, because abstinence-only sex education programmes also aim to reduce the risk of HIV transmission, and current data indicates that they are not effective at all.

Instead, these programmes are just churning out more young adults who are in denial about sex, but go ahead and boink each other anyway.

Maybe any abstinence-only programme ought to be preceded by a "promise-keeping" programme in order to work, but I wouldn't bet on the effectiveness of that.


Would you like to know more?

- Original review article (Underhill et al. 2007): Sexual abstinence only programmes to prevent HIV infection in high income countries