The risk of a sexually transmitted infection (STI) significantly decreases for serially monogamous individuals when the time between partners increases to longer than 4 months for women and longer than 6 months for men, according to a study published in JAMA Network Open.

Researchers in this survey study examined the associations between partnership timing (measured as time overlap or time period between partners) and risk of STIs, as well as the associations between partners’ perceptions of overlapping sexual partners and risk of infection. Data were collected from Britain’s third National Survey of Sexual Attitudes and Lifestyles (Natsal-3), which has a 57.7% response rate and is considered broadly representative of the general British population.

Participants aged 16 to 44 years were included if they reported having >1 sexual partners in the previous 5 years, and gaps between recent partners were calculated from the date of last sexual encounter with previous partner and initial sexual encounter with following partner. Study investigators denoted overlapping partnerships, termed concurrency, by negative gaps, whereas consecutive partnerships, termed serial monogamy was denoted by positive gaps.

Of the 8867 eligible participants, 39.6% were men and 58.2% [sic] were women (mean age, 28 years for both sexes). Of male participants, 48.1% reported >2 sexual partners and >1 time gaps between partners compared with 39.5% of female participants. The median time gap between partners was 2 months (range -3 to 8). Most of the participants reported at least 1 month between partners (67.0%), but these gaps were still sufficiently brief for the transmission of STIs.

A significant decrease in the risk of diagnosis of a STI was not seen until the time between partners reached >4 months for women (adjusted odds ratio [aOR] 0.39; 95% CI, 0.19-0.81) and >6 months for men (aOR 0.42; 95% CI, 0.20-0.85) compared with time overlaps of >2 years. Perceptions of partners’ concurrency (reporting no concurrency vs reporting concurrency) was independently associated with diagnoses STIs in women only (aOR 0.32; 95% CI, 0.22-0.49).

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Study investigators concluded that “[t]his study suggests the epidemiological importance of understanding the timing of partners in STI transmission, not just the timing of an individual’s partners but also of their partners’ partners.”

Reference

Mercer CH, Jones KG, Geary RS, et al. Association of timing of sexual partnerships and perceptions of partners’ concurrency with reporting of sexually transmitted infection diagnosis [published online December 14, 2018]. JAMA Netw Open. doi: 10.1001/jamanetworkopen.2018.5957