The human race has exercised fertility control since antiquity. The oldest medical recipe to prevent conception was written by the Egyptians around 1850 bc. The Greeks, in the 2nd century ad, not only distinguished between contraceptives and abortifacients, but also observed that prevention of conception is medically preferable to abortion. In more recent history, detailed contraceptive techniques were published by Charles Knowlton in 1832; contraceptive methods became widely available in the United Kingdom and other developed countries in the 1930s, and by the 1960s there was worldwide acceptance that fertility control was essential to curb the population explosion.

In developed countries, adolescents have been targets of pregnancy prevention strategies by communities since the late 1980s, as unintended teenage pregnancy is considered an adverse event for society and individuals. However, many of these initiatives, though embraced by many with enthusiasm and best intent and often at great financial cost, have not been evaluated, reported, or subjected to any rigorous scientific scrutiny.

Hence the two original articles in a recent issue of the BMJ are particularly welcome.^1,2 The Canadian investigators, DiCenso et al, undertook a meta-analysis of the results of 26 randomised controlled trials of published and unpublished interventions (including sex education classes, school or family planning based clinics, and other community based programmes). There was …