Background: Evidence suggests that young women experience high HIV burden shortly after onset of sexual activity. We compared the characteristics of first sex across young women engaged in formal sex work (SW), transactional sex (TS), and causal sex (CS) in Mombasa, Kenya.
Methods: We performed a bio-behavioural survey of 1,298 women aged 14-24 years, recruited from sex work hotspots. We classified participants as: self-identified SW; TS (an expectation of money/goods in return for sex but the price was not pre-negotiated); CS (no expectation that money/goods would be exchanged). We examined differences in first sex across the groups, and used multivariate logistic regression to examine the association between current sexual behaviour (SW, TS, CS) and a risky first sex (forced, condomless sex in exchange for money/goods).
Results: SW, TS and CS comprised 31.4%, 13.6% and 55.0% of the study population. SW were younger (median 15.5 years) at the time of their first sex (TS 16.0 yrs; CS 16.3 yrs; p< 0.001), a median of 1 year before 32% of SW self-identified as sex workers. First sex was more likely to be forced among SW (18.4%; TS 9.8%; CS 9.9%, p< 0.001), while the exchange of money/goods was highest in TS (58.8%; SW 45.1%; CS 39.0%, p<0.001). Nearly all (99%) first sex was condomless and anal sex was high across all groups (SW 30.2%; TS 45.7%; CS 43.6%). Compared to CS, and after adjusting for age at first sex and current age, a risky first sex was higher among SW (OR 2.1, 95% CI 1.1-3.8, p=0.02) but not among TS (OR 1.8, 95% CI: 0.83-3.8, p=0.1).
Conclusions: First sex occurs within a high-risk context across SW, TS, and CS in Kenya, and especially among SW. HIV prevention programs for young women should reach young women before they become sexually active.