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DiCenso et al, undertook a meta-analysis of the results of 26 randomised controlled trials of published and unpublished interventions (including sex education classes, school or family planning based clinics, and other community based programmes).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 no evidence that such interventions either delayed sexual intercourse, improved the use of contraception, or reduced the incidence of unintended pregnancy in adolescents.¹ The investigators from Scotland, Wight et al, published the long awaited interim report of a randomised trial comparing a speciallydesigned, intensive sex education programme for adolescents (SHARE) with conventional sex education in schools.² Six months after the intervention, there was no difference in sexual risk taking in the adolescents, despite an improved knowledge of sexual health. Data from this study on unintended pregnancy rates are not yet available.

These disheartening results should not come as a surprise to most of us working in the fields of sexual health. The questions that spring to mind are: Why does a young person, living in an affluent society, surrounded by the multitude of contraceptive options available to us in the 21st century, armed with the knowledge of the adverse consequences of unsafe sex, get pregnant? What can be done about it? The answer to both is: We don’t fully know.

Firstly, knowledge alone is not enough to bring about changes in behaviour. Few people are unaware of the harm of cigarette smoking, the dangers of speeding on the road, or the adverse effects of obesity. If knowledge alone were the solution, then these problems should already have disappeared, which outcome manifestly shows no likelihood of occurring any time soon.

Secondly, there are many personal, ethical, economic, and social reasons for uptake (or not) of safe sexual practices and pregnancy avoidance. Religious and ideological beliefs, biological urges, cultural and familial patterns, peer group pressure reflecting the power of modern mass media may all be more potent factors than messages of sex education in school. It is simplistic to attribute the low teenage pregnancy rate in the Netherlands to school sex education programmes alone. Their successful strategy also included mass media campaigns, open discussion on sexuality, strong desire to reduce reliance on abortion, and ongoing education.³ The response of young people to such strategies may depend on other less easily quantifiable factors such as sexual attitude and social mores. Recently studies of low income African-American adolescent females suggest high risk sex is associated with several elements in sexual dynamics such as having older boy friends,⁴ relationship pattern favouring male decision making, perceived invulnerability to acquiring STD,⁵ even positive beliefs about early parenthood.⁶ Hence what works for white teenagers in the Netherlands may not be applicable in the black neighbourhoods of Alabama, United States. We need large scale, longitudinal and, especially, culturally specific studies exploring the social determinants of unintended pregnancy and unsafe sexual practices in young people, to help us determine what interventions would be most effective for that particular population.

Why does a young person, living in an affluent society, surrounded by the multitude of contraceptive options available to us in the 21st century, armed with the knowledge of the adverse consequences of unsafe sex, get pregnant?

Thirdly, studies of factors leading to illicit drug or alcohol use in adolescents highlighted the effect of the influence of parents, peers, and behaviour of “the most admired person.” (Perhaps our football heroes can contribute more to our youth than national pride alone!) In addition, lack of self confidence and communication skills increased susceptibility to drug use.^7,8 In studies of sexual behaviour, teenage girls living in a perceived supportive family, where parents knew whom they were with, and reporting frequent communication with parents, were more likely to negotiate use of condoms and practise safe sex.^9,10 It could be argued that breakdown of the traditional family unit is the prime reason for the enormous social problem facing teenagers in Western society today. The rising pregnancy rate is a mere reflection of such social disintegration.

However, apparently insurmountable obstacles are not an excuse for nihilism. Encouragingly, there is some evidence that interventions are worth while. Teaching specific social skills to young adults at high school, coupled with at least 2 years of booster sessions, has been shown to be effective in drug misuse prevention.¹¹ Sex education may have more impact if started even earlier than junior high school. Children in kindergarden or early primary school are more susceptible to imprinting. Perhaps parental involvement in any sex education programmes, with renewed emphasis on parental supervision, may also be crucial for their success.

Finally, it is important to point out that statistics equate teenage pregnancy with unintended or unwanted pregnancy, which may not necessarily be true, especially for certain cultural and ethnic groups. Furthermore, we may need to ask ourselves why teenage pregnancy (as distinct from acquiring sexually transmitted infections) is considered a bad thing, and for whom? There is evidence that adolescent childbearing for some is the means of adapting to, rather the cause of, urban poverty so decreasing teenage pregnancy may have less impact on the socioeconomic wellbeing of the young family unit concerned.¹² The observed health related disadvantage of children born to teenage mothers may not be the result of maternal young age itself. It can be a consequence of other factors including the ethnic, economic,¹³ and family background of mothers,¹⁴ all of which are not readily amenable to correction by a simple strategy of sex education.

Lord Byron, as renowned as a philanderer as he was a poet, presumably knew whereof he spoke when he wrote in 1819: “The reading or non-reading a book - will never keep down a single petticoat.”¹⁵