The Prevalence, Frequency and Social Ecology of Sexual Concurrency Among Young Adult Women.

Context: Sexual concurrency among women is associated with increased risks of STD transmission, unintended pregnancy and sexual health disparities. Understanding the prevalence of concurrency-overlapping sexual partnerships-is imperative to reducing these disparities.

Methods: Weekly, population-representative panel data from 757 women aged 18-22, collected from 2008 to 2012 in Michigan, were drawn from the Relationship Dynamics and Social Life study. Univariate analyses assessed the prevalence of two forms of sexual concurrency. Multivariate logistic regression models investigated associations between women's social-ecological characteristics and concurrency.

Results: Twenty percent of women had vaginal intercourse with two partners in one week; 14% had intercourse with a second partner during an ongoing relationship. In both cases, the majority of individuals had intercourse with the second partner in one to three weeks in total. The likelihood of both types of concurrency was elevated among women who believed they should have sex with men after seeing them for a while (log-odds, 0.27 and 0.23, respectively) and among those who were Black (0.58 and 1.02, respectively); the likelihood was reduced among women who were more willing to refuse unwanted sex (-0.10 and -0.13, respectively) and who were in exclusive, cohabiting, or married or engaged relationships (-1.82 to -2.64). Having intercourse with multiple partners in one week was also associated with receiving sex education from parents, the degree that parents and friends approved of sex, and having had early intercourse without contraception.

Conclusions: Sexual concurrency among young women is prevalent but intermittent, and interventions that address individuals' social-ecological contexts are needed to reduce negative health outcomes.