Background:  Early sexual experience among men who have sex with men (MSM) may influence subsequent sexual risk behavior and may be changing over time. We explored secular trends in the circumstances of sexual debut among MSM and association with HIV infection.

Methods:  These analyses used data from MSM (age ³25) in the Urban Men’s Health Study (1996-1998), a population-based survey of US MSM (n = 2724). We used trend tests to assess differences in sexual initiation characteristics between 10-year birth cohorts (eg, born 1940-1949, 1950-1959, etc), and multivariate logistic regression to measure the association between these experiences and self-reported HIV infection.

Results:  Fewer men in recent birth cohorts reported a male first sexual partner (p <0.01) or only male sexual partners before age 18 (p <0.01) compared with men in earlier cohorts. Men in recent cohorts were more likely to report oral sex (p <0.01) or mutual masturbation (p <0.01) during their homosexual debut than earlier cohorts, but there was no difference in the proportion reporting anal sex. Childhood sexual abuse was more common in recent birth cohorts (p <0.01), as was harassment at school (p <0.01). Over time, age at oral sex debut and anal sex debut decreased (p <0.01 for both). Similarly, the ages for indicators of “coming out” (eg, first had boyfriend, wondered if gay, decided that gay, disclosed homosexuality) decreased over time (p <0.01 for all), although age when first attracted to men did not vary between cohorts. Adjusting for birth year, race, education, and city of residence, HIV infection was associated with more sexual partners before age 18 (OR 1.004 per partner, 95%CI 1.00 to 1.01), oral sex (OR 1.5, 95%CI 1.1 to 2.1), or anal sex (OR 1.9, 95%CI 1.3 to 2.8) during first sex with a male, younger age at homosexual debut (OR 0.97 per year, 95%CI 0.9 to 1.0), younger age when first had a boyfriend (OR 0.96, 95%CI 0.9 to 1.0), living in a suburb (OR 1.6, 95%CI 1.1 to 2.2) or small city (OR 1.4, 95%CI 1.0 to 1.9) compared to a large city during first sex with a male, and parental substance abuse (1.5, 95%CI 1.1 to 1.9).

Conclusions:  These data suggest that MSM in recent birth cohorts have a broader early sexual repertoire than MSM in earlier cohorts, and some of these experiences are associated with HIV infection. Longitudinal sexual behavior data from young MSM are needed to further elucidate the influence of early behavior patterns on subsequent sexual risk.