Developed by the Centro de Medicina Reproductiva y Desarrollo Integral del Adolescente (CEMERA) at the Facultad de Medicina de la Universidad de Chile, this 2-year project sought to provide comprehensive sex education - bolstered by training and the preparation of a printed manual for teachers, among other activities - for in-school adolescents (ages 12 to 17) in the metropolitan area of Santiago, Chile.

CEMERA obtained approval from the Ministry of Education, other government entities, the schools, and parents to provide the programme in the two intervention sites in Santiago; comparison schools were also in Santiago. At baseline, knowledge of sexuality and reproduction, contraception, and sexually transmitted infections (STIs) including HIV was similar among young women in intervention and comparison schools; knowledge levels were also similar among young men in intervention and comparison schools. For example, 66.2% of female students in intervention schools (and 65.9% of male students) correctly answered questions relating to contraception, as did 64.2% of young women (and 63.9% of young men) from comparison schools. The proportions of women and men with sexual experience were somewhat higher among youth in comparison schools, especially among young men (e.g., 30.7% of men in intervention schools reported ever having had sexual intercourse, versus 41.7% in comparison schools).

The quasi-experimental case control cohort study was carried out in 2 intervention schools and 3 control schools. The baseline anonymous survey was conducted with 4,448 students, including 2,512 in intervention schools and 1,936 in comparison schools. The 21-month follow-up was conducted with 4,169 students: 2,249 at the intervention schools, and 1,920 at the comparison schools. The 33-month follow-up was conducted with 4,129 students, including 2,192 at the intervention schools and 1,937 at the comparison schools.

Between baseline and 21-month follow-up, knowledge of sexuality, reproduction, contraception and STIs, including HIV, increased significantly more among youth in intervention schools versus those in comparison schools. Specifically, in the intervention schools knowledge scores on sexuality and reproduction increased from 57% to 72% among young women and from 51% to 68% among men; in comparison schools, knowledge increased from 55% to 62% among young women and from 47% to 55% among young men. Knowledge of contraception increased from 66% to 82% among young women and from 66% to 80% among males in the intervention schools; among students in comparison schools, contraceptive knowledge increased from 64% to 73% among women and from 64% to 72% among men. Finally, knowledge of HIV/STIs increased from 67% to 86% among women and from 72% to 88% among men in intervention schools; among students in comparison schools, HIV/STI knowledge increased from 62% to 72% among women and from 69% to 79% among men.

The evaluation found that this programme resulted in a delayed initiation of sexual intercourse:

• Among women, the proportion in the intervention schools reporting sexual initiation rose from 17% at baseline to 28% at 21-month follow-up and 30% at 33-month follow-up. By contrast, reports of sexual initiation among women in comparison schools rose from 21% at baseline to 34% at 21-month follow-up and 37% at 33-month follow-up. These effects were statistically significant, at both follow-up points.
• Among men, the proportion in the intervention schools reporting sexual experience at baseline was 31% rising to 36% at 21-month follow-up and to 42% at 33-month follow-up. By contrast, the reports of sexual experience among men at comparison schools rose from 42% at baseline to 45% at 21-month follow-up and to 49% at 33-
  month follow-up. These effects were statistically significant, at both follow-up points.

Evaluators found a statistically significant increase in contraceptive use among
sexually experienced female students in the intervention schools versus sexually experienced female students from comparison schools. All comparsions noted below concern sexually experienced young women surveyed between baseline and 33-month follow-up:

• Middle school, class one: a rise in contraceptive use from 14 to 51% in the intervention group versus a rise from 17% to 30% in the comparison group
• Middle school, class two: a rise in contraceptive use from 29 to 56% in the intervention group, versus a rise from 24% to 43% in the comparison group
• Middle school, class three: a rise in contraceptive use from 33 to 67% in the intervention group, versus a rise from 31% to 45% in the comparison group
• Middle school, class four: a rise in contraceptive use from 43 to 73% in the intervention group, versus a rise from 38% to 56% in the comparison group.

At follow-up, evaluators found a statistically significant decline by about one-third in the proportion of young women from the intervention schools who became pregnant (down from 15% to 10%). In the comparison schools, the decline was not significant. The difference between intervention and comparison schools was also statistically significant (p<0.05). Furthermore, the programme resulted in a reduced incidence of imposed abortion. Among students who became pregnant, there was a decline in imposed abortions in the intervention sites from 3% to 0%. By contrast, evaluators found an increase in imposed abortions among pregnant students in the comparison schools (4% rising to 14%). These net declines were statistically significant.