Mean Age of First Sex: Do They Know What We Mean?

Early age at first sexual intercourse is a particularly important variable for public health policy makers. It is associated with specific unhealthy behaviors, such as having unprotected sex on first sexual intercourse,condommisuseorhavingmultiple (concurrent or lifetime) partners (Kaestle, Halpern, Miller, & Ford, 2005; Louie et al., 2009). These can lead to higher rates of sexually transmitted infections (STIs), teenage pregnancy, and adverse psychological consequences, such as feelings of disappointment and regret (Campbell, 2008; CDC, 2008; Eshbaugh & Gute, 2008; Ma et al., 2009; Vaccarella et al., 2006; Wight et al., 2008). In the light of the role played by the delay of first sexual intercourse and mutual monogamy in curtailing STI epidemics (Halperin et al., 2011; Potts et al., 2008), the Joint United Nations Program on HIV/AIDS (UNAIDS) has introduced changes in its yearly reports on the global AIDS epidemic: in addition to condom use, they now report age of sexual initiation and multiple partnerships in different countries as a means of more comprehensively following up on all the determinants of the epidemic (UNAIDS, 2006, 2008). However, the information concerningageof sexual initiation can be conveyed in different ways. For instance, UNAIDS usually reports the ‘‘proportion, among 15–19-year-olds, having had sex byage 15’’(UNAIDS, 2008) whereas other sources use the ‘‘mean age at first sexual intercourse’’ alone or in combination with‘‘proportions having already had sex at given ages’’ (Avery & Lazdane, 2008; Kaestle et al., 2005; Manlove, Ikramullah, Mincieli, Holcombe, & Danish, 2009; Rosenbaum, 2009).Averageagesatfirst sexual intercourse lackprecision in describing the extent of sexual experience at different ages. They are sensitive toextreme values and sensitive to the ranges of ages of the persons included in the survey. For example, a plausible wrong interpretation of the statement that‘‘the mean ageofsexual initiation is15 years’’is that‘‘mostyouth’’aged15 are having sex when, in fact, the contrary may be true. Average ages at first sexual intercourse, obtained from published epidemiological studies about sexuality, are often conveyed by the media in such a way that it does not necessarily grasp the subtleties entailed in such data. The targets of media, such as the general population and indeed young people themselves, can, in turn, be misled. Sentences derived from average data such as this one—‘‘compared with previous generations, young people (16–20 year-olds) were having intercourse for the first time at an earlier age, on average at 16.5 years of age’’ (Avery & Lazdane, 2008)—leave the facts as to how many from these age groups have, in fact, had sex unspecified. These confusing interpretations of epidemiological data create definite impressions that can be misleading and thus may hinder public health and educational interventions that are trying to delay sexual initiation in youth (Halperin et al., 2004). As Rose (1992) affirmed years ago, ‘‘It doesn’t make much sense to expect that individuals will behave differently from their peers; J. de Irala (&) S. Carlos C. López-del Burgo Preventive Medicine and Public Health, School of Medicine, University of Navarra, 31080 Pamplona, Spain e-mail: [email protected]