RESUMO
Increasing rates of mobile phone access present potential new opportunities and risks for adolescents' sexual and reproductive health in resource-poor settings. We investigated associations between mobile phone access/use and sexual risks in a cohort of 10-24-year-olds in South Africa. 1563 adolescents (69% living with HIV) were interviewed in three waves between 2014 and 2018. We assessed mobile phone access and use to search for health content and social media. Self-reported sexual risks included: sex after substance use, unprotected sex, multiple sexual partnerships and inequitable sexual partnerships in the past 12 months. We examined associations between mobile phone access/use and sexual risks using covariate-adjusted mixed-effects logistic regression models. Mobile phone access alone was not associated with any sexual risks. Social media use alone (vs. no mobile phone access) was associated with a significantly increased probability of unprotected sex (adjusted average marginal effects [AMEs] + 4.7 percentage points [ppts], 95% CI 1.6-7.8). However, health content use (vs. no mobile phone access) was associated with significantly decreased probabilities of sex after substance use (AMEs -5.3 ppts, 95% CI -7.4 to -3.2) and unprotected sex (AMEs -7.5 ppts, 95% CI -10.6 to -4.4). Moreover, mobile phone access and health content use were associated with increased risks of multiple sexual partnerships in boys. Health content use was associated with increased risks of inequitable sexual partnerships in adolescents not living with HIV. Results suggest an urgent need for strategies to harness mobile phone use for protection from growing risks due to social media exposure.