Abstract

Background: Age at first sex (AFS) is associated with adverse outcomes. We explore associated factors and correlates of ‘early’ AFS (<16 years). Methods: In 2009–11, participants (16–29 years) were recruited. Multivariate Cox regression explored correlates of AFS. Logistic regression analysis explored associations between early AFS and risk behaviours. Results: Of 3563 participants, 79% were sexually active. Median AFS was 17 years. Compared with those aged 25–29 years, younger participants reported younger AFS [16–17 years: adjusted hazard ratio (AHR) = 1.87, P < 0.01; 18–19 years: AHR = 1.47, P < 0.01, 20–24 years: AHR = 1.19, P < 0.01]. Of those sexually active, 29% reported early AFS. Early AFS was associated with being male [adjusted odds ratio (AOR) = 1.25, P < 0.05], being younger (16–17 years: AOR = 11.10, P < 0.01; 18–19 years: AOR = 3.60, P < 0.01; 20–24 years: AOR = 1.83, P < 0.01; compared with 25–29 years), having no education after high school (AOR = 1.52, P < 0.01), living alone (AOR = 1.84, P < 0.01) or with a partner (AOR = 1.57, P = 0.01), having more than five lifetime sex partners (AOR = 3.22, P = 0.01), inconsistent condom use in the past 12 months (AOR = 1.43, P < 0.01), ever using illicit drugs (AOR = 1.69, P < 0.01) and ever injecting drugs (AOR = 3.45, P < 0.01). Conclusions: The results highlight the importance of comprehensive sex education.