New research suggests yet another reason why sex education should be taught in the classroom – because teens can learn from each other how to successfully use contraceptive methods.

When I was a girl my father came into my room one afternoon and asked if I knew how babies were made. I said yes, because while I knew nothing about reproduction I was pretty certain that I did not want to learn about it from him. He was satisfied, and relieved, that I didn’t need a sex talk, and that was the end of that awkward conversation.

Looking back, I have no idea why this job fell to my father rather than to either my mother or older sister, but perhaps the women in my family were hoping that I would learn about sex the old fashioned way – from my friends at school.

Taking advantage of an area of economic research that has opened up in recent years – considering peer group effects – a new paper shows that if we want young people to adopt new technologies that are personal in nature then individual learning is probably the wrong approach.

Economists Emily Oster (University of Chicago) and Rebecca Thornton (University of Michigan) conducted a controlled experiment during which girls in grade seven and eight were given menstrual cups and taught how to use them in a one-time session. The girls were then asked to name their closest friends and followed for eighteen months to see if they managed to successfully adopt this technology.

These researchers found that one of the most significant determinants as to whether a girl was successful at using the menstrual cap until the end of the study (and more than half were) was having one, or more, close friends who were also using the menstrual cup — two months into the study, having one additional friend with access to the menstrual cup increased the probably a girl was successful at using hers by 19 percentage points.

And the principal reason for that success was not because it made girls more interested in trying to use the cap, but rather it made them more likely to succeed when they did.

Menstrual cups are not a contraceptive technology, obviously, but they are similar to contraceptives in that they are private and related to reproductive health. It is not difficult to imagine that the adoption of contraceptive technologies, like the NuvaRing for example, would be subject to the same peer group effects as those observed in this study.

There is a tendency to believe that we should protect our children from their peers, that all the effects are negative, but this is an excellent example of how we can take advantage of peer group effects. By targeting groups of teens, instead of individuals, we could improve the adoption of technologies that could lead to lower rates of teen pregnancy and sexually transmitted disease.



Oster, Emily and Rebecca Thornton (2012). “Determinants of Technology Adoption: Peer Effect in Menstrual Cup Take-Up.” NBER Working Paper No. 14828