Commentary

We know that a variety of health interventions can change youth attitudes and knowledge. More controversial is whether such interventions can change complex sexual behaviors such as delaying sexual initiation or increasing contraceptive use. The most important question, however, is whether the interventions can affect biological outcomes such as unintended pregnancy or sexually transmitted infections by changing behaviour.

The systematic review by DiCenso et al found that primary prevention strategies did not delay initiation of intercourse, improve contraceptive use among young men and women, or reduce pregnancies in young women. Why do these interventions appear so ineffective? Firstly, a paucity of high quality trials have been published. Only 2 of the studies met all 4 of the authors’ quality criteria. Secondly, because every study did not systematically examine each of the key dependent variables, the comparisons are sporadic at best. Thirdly, the heterogeneity of the specific interventions presents difficulties in analysis and interpretation. Some interventions lasted 3 months, whereas others lasted 3 years. Fourthly, the study populations were quite different. Some studies included only sexually active youth, whereas others included both virginal and sexually experienced youth. An accurate assessment of exposure to pregnancy risk is important; that is, we need to know whether youth were sexually active after the intervention.

The current evidence is insufficient to show that any pregnancy prevention intervention definitively affects behaviour or biological outcomes. We need improvements in conceptualising the problem, implementing the interventions, designing the evaluation, and analysing the data. In an ideal study, the intervention would be clearly defined and would target youth before they become sexually active. The samples would be large and include both men and women from a range of income and ethnic groups. Study outcomes would be assessed over a period of years, and would include pregnancies and births, as well as programme costs. Given the political, bureaucratic, and resource limitations of research involving youth, it is doubtful that such a Rolls Royce approach is feasible or affordable. However, this is the type of information needed to show whether adolescent reproductive behaviours can be changed.