The generational effect on age disparate partnerships and the risk for human immunodeficiency virus and sexually transmitted infections acquisition.

In South Africa, a large proportion of young women are in age disparate relationships, which is believed to be a risk factor for human immunodeficiency virus (HIV). The aim of this study was to determine the generational effect of age disparity on HIV and sexually transmitted infection (STI) incidence. Socio-demographic and behavioural data were collected from women, aged 16 and older, who were followed for up to 24 months. Women who reported having a steady sexual partner older than themselves were categorised into: (1) non-age disparate partnerships (age difference between partners was 0-4 years); (2) intra-generational age disparate partnerships (5-9 year age gap between sexual partners); and (3) inter-generational age disparate partnerships (age gap of 10 years or more between sexual partners). Of the 1355 women included in the analysis, 759, 429 and 167 were in non-age disparate, intra-generational age disparate and inter-generational age disparate partnerships, respectively. Strong predictors of inter-generational age disparate partnerships include age, marital status and concurrency of sexual partners. No significant relationship between age disparity and risk of HIV acquisition was found. The highest crude STI incidence was observed among those in intra-generational age disparate relationships followed by those in non-age disparate relationships (31.86 [26.41-38.44] and 25.60 [21.92-29.91] per 100 person-years, respectively). Reduction of multiple partnerships remains key to HIV prevention; however, in light of partner concurrency being more prevalent than individual concurrency partnerships, female-initiated HIV prevention options remain critical.