Letters

Reducing unintended pregnancy among adolescents

Authors did not give balanced interpretation of their findings

Changes in social, economic, and educational policy need to be taken into account

Authors did not give balanced interpretation of their findings

EDITORDiCenso et al provided a rigorous, systematic review of randomised, controlled trials to reduce unintended pregnancies in adolescents.¹ They did not, however, provide a balanced interpretation of their findings. Specifically, the main research question in the study and the conclusions that were drawn from it are inconsistent. Since within 21 of 26 trials reviewed, or 81%, the control condition was actually conventional sex education, this was not a study about whether or not sex education works.

Rather, this was a study that compared the efficacy of theory driven sex education with conventional sex education. What DiCenso et al found, contrary to previous findings,² is that theory driven sex education did not outperform conventional sex education. The strongest conclusion that can be drawn is that in this select group of studies, the two conditions come out equal in terms of behavioural outcomes. It is troubling that DiCenso et al point this out only late in their paper as essentially an afterthought.

In addition, given the study's findings, it would seem crucial for DiCenso et al to suggest answers to this question: Why are some sex education programmes successful and others are not? Despite 10 hypotheses tested and considerable heterogeneity among studies, they were not able to answer this question. As a result it seems that the field is no further ahead in understanding this now than it was before this study. At the very least, DiCenso et al could have better addressed this issue, as others have done.²

My objection is not to the study. Such reviews can and often do help move the field forward. Rather, as I have said previously,³ my objection is to conclusions drawn from a study that did not ask the questions in the context of that study. Since nearly all of the adolescents in these trials received some type of sex education, we cannot know what the natural trajectory of behaviour would have been without such education. Thus the strongest interpretation of these data is that theory based programmes did not have more impact than conventional programmes, within the set of studies reviewed. Although this runs counter to much of the literature in this field, ^{2 4 5} it is the result of this particular review and one that demands further interpretation and exploration.

Seth M Noar, senior research associate. 
HIV Prevention Research, Department of Communication, University of Kentucky, Lexington, KY 40506, USA

Changes in social, economic, and educational policy need to be taken into account

EDITORTwo recent papersa systematic review and a randomised controlled trialreport little or no influence of primary preventive interventions and sex education on teenage sexual activity and unintended pregnancy in adolescents. ^{1 2} A recent BMJ news item may hold the key to these disappointing findings.³

View larger version (24K): [in this window] [in a new window]   Teenage birth rates by literacy distribution among 13 countries in the Organisation for Economic Cooperation and Development (OECD) 4 5

The systematic review identified 22 studies, 21 from the United States and one from Canada.¹ The randomised controlled trial was conducted in Scotland.² The United States (52.1 births/1000 women 15-19 years) is first, the United Kingdom (30.8 births/1000) second, and Canada (20.2 births/1000) eighth highest in the league table of teenage births among 28 rich nations.³ It is likely that in these countries more powerful factors are at work limiting the effectiveness of short term, education based interventions.

Although open attitudes to adolescent sexuality and availability of contraception all contribute to the Dutch success in reducing teenage pregnancies,³ a further important underlying factor considered in a Unicef report but not mentioned in the BMJ news item, is the relation of teenage births to income and educational inequality.⁴ Teenage birth rates/1000 women aged 15-19 years are positively correlated (r=0.44, P<0.05) with income inequality (the Gini coefficient based on per capita household income) among 25 countries in the Organisation for Economic Cooperation and Development (OECD).⁴ The figure shows a strongly positive correlation (r=0.91, P<0.01) between teenage birth rates and literacy distribution (90th centile/10th centile) among the 13 OECD countries participating in the international adult literacy survey 1994-8.⁵

Limited interventions, such as school based sex education, abstinence programmes, and family planning clinics could not realistically be expected to overcome the powerful forces generating inequality that are prevalent in the United States, the United Kingdom, and Canada. Reduction in teenage birth rates in these countries is likely to depend as much on changes in social, economic, and educational policy as on school based sex education.

Nick Spencer, professor of child health. 
School of Postgraduate Medical Education, University of Warwick, Coventry CV4 7AL n.j.spencer{at}warwick.ac.uk