Correlates of Adolescent and Young Adult Sexual Initiation Patterns

Sexual activity before marriage is now the typical developmental pathway for most U.S. adolescents and young adults. In recent national surveys, approximately 47 percent of 9th−12th graders reported ever having vaginal intercourse (1). By their late twenties, approximately 90% of males and females have engaged in vaginal sex (2). Noncoital sexual activity is also common among youth; more than half of adolescents (aged 15–19 years) have received or performed oralgenital sex, and approximately 11 percent have engaged in anal sex (3). Noncoital sexual activity is higher among youth who have had vaginal sex; 87 percent also report oral-genital sex and 21 percent also report anal sex (3). Although the emergence of sexual expression during adolescence and early adulthood is nearly universal, little is known about patterns of initiation – including the timing, sequencing, and spacing of different sexual behaviors – or the determinants of those patterns. Most research on adolescent sexual behavior has focused on the predictors and implications of the timing and circumstances of first vaginal intercourse. Although first vaginal intercourse is clearly an important transition, adolescents engage in other types of sexual behavior that also have implications for health and well-being. Different factors may determine initiation of these behaviors (3), and reducing adolescent sexuality to a single event or behavior (i.e., transition to first intercourse) does not allow examination of normative developmental processes. An understanding of normative processes requires the consideration of adolescent sexuality in the context of broader development, includes a full repertoire of sexual and romantic experiences, and examines how these various behaviors interact with other biological, psychological, and social factors to contribute to the emergence of a sexual self (4). Integrating information about timing, sequencing, spacing, and variety of sexual behaviors may provide greater explanatory power for multiple aspects of later well-being than simply examining these measures in isolation. Prior Research on Patterns of Sexual Initiation In one of the first studies to describe multifaceted patterns of sexual initiation in a nationally representative sample of adolescents, Haydon et al. used latent class analysis (LCA) to group adolescents in the National Longitudinal Study of Adolescent Health (Add Health) into one of five latent classes on the basis of first sexual behavior initiated (vaginal, oral-genital, or anal sex), timing of first sexual experience, number/variety of behaviors, spacing between first and second behavior, and whether anal sex was initiated before age 18 (4). Respondents who initiated vaginal sex first and then waited at least 1 year before initiating another behavior (typically oral-genital sex, as less than 10% reported anal sex before age 18 years) comprised the largest class (Vaginal Initiators/Multiple Behaviors; 49%). The second largest class (Dual Initiators; 32%) consisted solely of respondents who initiated oral-genital and vaginal sex within the same year and did not have anal sex during adolescence. In the third class (Vaginal Initiators/Single Behavior; 8%) more than three-quarters of its members had only engaged in one type of behavior (typically vaginal sex). The two most statistically atypical classes were the Postponers (6%) and Early/Atypical Initiators (6%). Postponers delayed all sexual activity until almost 22 years of age, on average, but reported a relatively fast progression once sexual initiation had occurred; 85% of respondents in this class initiated oral-genital and vaginal sex within the same year. In contrast, the Early/Atypical class was characterized by an early age of initiation (15 years, on average) in combination with initiation of two or more behaviors within the same year. Most significantly, all Early/Atypical Initiators reported having had anal sex by age 18. Two later papers examined the implications of these sexual initiation patterns for selected aspects of young adult sexual and reproductive health. First, Haydon et al. investigated associations with several indicators of sexual risk-taking: diagnosis of sexually transmitted diseases (STDs), concurrent sexual partners, and exchanging sex for money (5). They found that although Postponers had lower odds of each outcome relative to the normative class (i.e., Vaginal Initiators/Multiple Behaviors), Early/Atypical Initiators had outcomes similar to those of the normative class. Early/Atypical Initiators also had a higher likelihood of reporting concurrent sexual partnerships but were no more likely to report STDs or exchanging sex for money. Subsequently, Huerta, Harris, and Halpern (working paper) examined the association between class membership and romantic relationship satisfaction in young adulthood (6). Findings parallel those of Haydon et al. Specifically, controlling for relationship type (marriage, cohabitation, dating), Postponers reported better romantic relationship satisfaction than the normative class. However, Early/Atypical Initiators did not differ from the normative class in satisfaction. In a separate but related set of analyses of Add Health data, Reese et al. found that adolescents who initiated oral sex first, and waited at least a year before having vaginal intercourse, were significantly less likely to experience a pregnancy during their teenage years (7). Collectively, these findings suggest potential benefits of sexual postponement, but also indicate that other, less common (and seemingly more risky) patterns of initiation are not necessarily associated with negative consequences for the outcomes examined to date. Emergent sexual patterns likely reflect multiple influences. Although few studies have documented factors associated with the debut of noncoital behaviors, there is a large literature documenting factors associated with the initiation of vaginal sex, implicating sociodemographic characteristics (e.g., lower socioeconomic status, single parent households) (8), early pubertal timing (9–10), poor family communication (11), lower attachment to conventional institutions such as family, school, or religion (12–13), and general psychosocial or behavioral unconventionality, especially engagement in nonsexual risk behaviors such as smoking and drug use (14). Whether factors that predict vaginal initiation are similarly associated with noncoital behavior, and more specifically with complex patterns of sexual initiation, is not known.