Abstract
PURPOSE: Sexual partnerships that overlap in some period of time (i.e., concurrent) are a key factor in sexually transmitted infection (STI) transmission. Research examining concurrency among adolescents typically uses person-level, cross-sectional, and/or retrospective data, obscuring factors that manifest on any given occasion of concurrency. We used sexual diaries to examine: (1) daily prevalence of vaginal sex concurrency when two partners are reported by adolescent women; and (2) individual, relational, and behavioral attributes that impact the likelihood of sex with neither partner, with one partner or the other, or with both partners on any given day. METHODS: Daily diaries were drawn from a large longitudinal cohort study examining sexual relationships, behaviors, and STIs among adolescent women. Participants contributed 280,844 partner-associated diary entries, of which (27.9%; n = 78,356) indicated multiple partners. All two-partner diary entries were retained for analysis (N = 323; Mage = 17.55; 90% African American). Random intercept mixed-effects multinomial logistic regression was used to evaluate the impact of predictor variables on odds of having sex with one or the other, both, or neither partner. RESULTS: Most two-partner days (93.5%) involved no sex with either partner. Few reports (.2%) indicated same-day sexual concurrency. Older age, greater partner support, and higher sexual interest increased the likelihood of sex with both partners on the same day. CONCLUSIONS: Individual, relational, and behavioral factors predict concurrency in ways that challenge assumptions that secondary partnerships constitute negligible relationships. Programs targeting partner concurrency in adolescents may find success tailoring messaging around these findings.