title: Who's cheating? Agreements about sexual exclusivity and subsequent concurrent partnering in Australian heterosexual couples.
abstract: Background Concurrent relationships are a driver of generalised epidemics of sexually transmissible infections (STIs). In Australia, explicit negotiation of agreements about sex outside regular relationships has been recommended in health promotion for gay men but not for heterosexuals.
  
  
  OBJECTIVE
  To ascertain the annual incidence of concurrency among people in ongoing male-female relationships according to their reported expectations of exclusivity.
  
  
  METHODS
  In a national cohort recruited by household random digit dialling in 2004-05, people aged 16-64 years completed computer-assisted telephone interviews including questions about expectations of sexual exclusivity, discussion and agreements. A year later, those in ongoing sexual relationships (5323 people) were asked about sexual partner numbers in the past year.
  
  
  RESULTS
  The huge majority (96%) expected sexual exclusivity of themselves and their partner. However, only 48% of men and 64% of women had discussed the matter and explicitly agreed. Older respondents were less likely to report discussion. Only 1% reported mutually nonexclusive ('open') relationships. A year later, 93% of respondents were still in the same relationship, among whom 4% of men and 2% of women had had sex outside the relationship. Those with agreements that one or both partners could have sex with others were more likely to do so, but the majority of respondents who had sex with someone else were in relationships that were explicitly or implicitly expected to be exclusive.
  
  
  CONCLUSIONS
  Sexual health promotion should stress the importance of STI testing and establishing agreements about exclusivity before condoms are abandoned in new relationships.
authors.affiliation: School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Juliet
authors.initials: J
authors.lastname: Richters
authors.affiliation: Australian Research Centre in Sex, Health and Society, La Trobe University, 215 Franklin Street, Melbourne, Vic. 3000, Australia.
authors.forename: Wendy
authors.initials: W
authors.lastname: Heywood
authors.affiliation: Australian Research Centre in Sex, Health and Society, La Trobe University, 215 Franklin Street, Melbourne, Vic. 3000, Australia.
authors.forename: Marian K
authors.initials: MK
authors.lastname: Pitts
authors.affiliation: School of Health and Social Development, Deakin University, 221 Burwood Highway, Burwood, Vic. 3125, Australia.
authors.forename: Julia M
authors.initials: JM
authors.lastname: Shelley
authors.affiliation: School of Public Health, University of Sydney, NSW 2006, Australia.
authors.forename: Judy M
authors.initials: JM
authors.lastname: Simpson
authors.affiliation: Australian Research Centre in Sex, Health and Society, La Trobe University, 215 Franklin Street, Melbourne, Vic. 3000, Australia.
authors.forename: Kent
authors.initials: K
authors.lastname: Patrick
authors.affiliation: Australian Research Centre in Sex, Health and Society, La Trobe University, 215 Franklin Street, Melbourne, Vic. 3000, Australia.
authors.forename: Anthony M A
authors.initials: AM
authors.lastname: Smith