Among 13 to 14 year-old girls who received either peer-led or teacher-led sex education, abortion rates by the age of 20 were the same — 5 percent — regardless of the education method, a study shows.

This may "temper high expectations" regarding the long-term impact of peer-led sex education, Judith Stephenson, of University College London, and colleagues comment in PLoS Medicine, a journal from the Public Library of Science.

However, there were some indications that the peer-led program reduced unwanted pregnancies, and Stephenson's group suggests further investigation of pupil-led sex education programs as part of a broader strategy to minimize teenage pregnancies.

"Peer-led sex education is widely believed to be an effective approach to reducing unsafe sex among young people, but reliable evidence from long-term studies is lacking," Stephenson and colleagues note.

The Randomized Intervention trial of Pupil-led sex Education, known as the RIPPLE trial, compared the efficacy of peer-led versus teacher-led sex education delivered to over 9000 male and female 8th grade students in the United Kingdom.

Peer-led sessions, conducted by specially trained older students, focused on information similar to that offered in the teacher-led program.

Follow-up through the age of 20.5 years showed 7.5 percent of girls taught in peer-led session had unintentional pregnancies compared with 10.6 percent of those taught in teacher-led sessions. This difference wasn't significant from a statistical standpoint, but the reduction in unintended pregnancies before age 18 was significant — 7.2 percent versus 11.2 percent.

As noted, however, the investigators found no difference in the number of girls having abortions, and there were no differences in teens' reports of unprotected first sex, pressured sex, sexually transmitted diseases, contraception practices or use, or in the percentage of boys or girls reporting sex before age 18.

In a related commentary, Dr. David A. Ross, from the London School of Hygiene and Tropical Medicine, points out that the use of actual, rather than self-reported abortion and pregnancy data is the major strength of the Ripple trial.

However, "it does not tell us how effective either intervention was relative to no sexual health education," Ross told Reuters Health. Therefore, development and rigorous evaluation of approaches to reduce teens' adoption of risky sexual behaviors should continue, he said.