Changes over time in sexual behaviour among young people with different levels of educational attainment in Tanzania.

BACKGROUND: HIV prevalence trends in Tanzania differ between socioeconomic groups. While HIV prevalence was initially higher among those with higher levels of educational attainment, it has fallen fastest among these groups. Among those with lower levels of education HIV prevalence has been stable. The behavioural dynamics underlying this phenomenon remain unclear, and a theory to guide interpretation of these trends and enable predictions of future patterns has not emerged. METHODS: We analysed data from two large nationally representative surveys conducted in Tanzania in 2003/2004 and 2007/2008. We focused on young people aged 15 to 24 years and explored reports of (i) first sex, (ii) having had more than one sexual partner in the last year and (iii) unprotected last sex with a non-cohabiting partner. Our analysis explored whether the behaviours differed by educational attainment in 2003/2004 and in 2007/2008, and whether changes over time in these behaviours differed between educational groups. RESULTS: The rate of first sex was lower among more educated males in 2007/2008 but not in 2003/2004, and among females in both surveys. The change over time in educational patterning of the rate of first sex in males was mostly due to a declining rate among the secondary educated groups. Among males, having had more than one sexual partner in the last year was associated with lower education in 2003/2004 and in 2007/2008. Among females, those with less education were more likely to report more than one partner in 2003/2004, although by 2007/2008 there was little association between education and reporting more than one partner. Unprotected last sex with a non-cohabiting partner was less common among the more educated. Among both sexes this decreased over time among those with no education and increased among those with secondary education. CONCLUSIONS: Patterns of behaviour suggest that differences in HIV incidence might explain trends in HIV prevalence among different educational groups in Tanzania between 2003/2004 and 2007/2008. The "inverse equity hypothesis" from child health research might partially help explain the changing social epidemiology of HIV incidence in Tanzania.