A Cochrane review [Abstract] 1 included 53 studies with a total of 105 368 adolescents. 18 studies randomized individuals, 32 randomized clusters (schools 20, classrooms 6, communities/neighbourhoods 6), and 3 studies were mixed (individually and cluster randomized). The length of follow up varied from 3 months 7 years. Combination of educational, skill building and contraception promotion lowered significantly the rate of unintended pregnancy among adolescents (RR 0.66, 95% CI 0.50 to 0.87; 4 individual RCTs, 1905 participants). Evidence on the possible effects of interventions on secondary outcomes (initiation of sexual intercourse, use of birth control methods, abortion, childbirth, sexually transmitted diseases) is not conclusive.
Educational interventions were unlikely to significantly delay the initiation of sexual intercourse among adolescents compared to controls (RR 0.95, 95% CI 0.71 to 1.27; 2 studies, 672 participants).
Educational interventions significantly increased reported condom use at last sex in adolescents compared to controls who did not receive the intervention (RR 1.18, 95% CI 1.06 to 1.32; 2 studies, 1431 participants). However, it is not clear if the educational interventions had any effect on unintended pregnancy as this was not reported by any of the included studies.
For adolescents who received contraceptive-promoting interventions, there was little or no difference in the risk of unintended first pregnancy compared to controls (RR 1.01, 95% CI 0.81 to 1.26; 2 studies, 3,440 participants).The use of hormonal contraceptives was significantly higher in adolescents in the intervention group compared to those in the control group (RR 2.22, 95% CI 1.07 to 4.62; 2 studies, 3,091 participants).
Comment: The quality of evidence is downgraded by study quality (possible self-report bias and various methodological limitations) and by inconsistency (heterogeneity in interventions and outcomes).
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