The contexts of sexual involvement and concurrent sexual partnerships.

CONTEXT Concurrent sexual partnerships may facilitate the spread of STDs, but little is known about partnership concurrency and its association with the relationship contexts of sexual involvement. METHODS Data about demographic characteristics, sexual histories and the most recent opposite-sex partnership among 783 adults aged 18-59 were drawn from the 1995 Chicago Health and Social Life Survey. Wald chi-square tests assessed gender differences in the timing and type of sexual involvement and in concurrent partnerships; bivariate probit regression analyses examined associations between concurrent partnerships and sexual involvement and other characteristics. RESULTS One in 10 of both women and men reported that both they and their partners had had other partners. Men were more likely than women to have been nonmonogamous (17% vs. 5%), and women were more likely than men to report that their partner had been (17% vs. 8%). The probability of having been nonmonogamous was 44% higher among women who were sexually involved with a friend, and 30% higher among those with a casual partner, than among those in a serious relationship; the corresponding figures for their partners were 48% and 32%, respectively. For men, the probability of having been nonmonogamous was elevated by 25% among those who were sexually involved with a friend and by 43% among those with a casual partner; for their partners, the figures were 27% and 24%, respectively. CONCLUSIONS Increased awareness that nonromantic sexual involvement is associated with partnership concurrency may enhance individuals' understanding of the risks and rewards of their relationships.