Association of various socio-demographic and risk characteristics with age at first sex
| Age at first sex (quintiles) | p Value | |||||
| 1st Quintile <15 years | 2nd Quintile 15–16 years | 3rd Quintile 17–18 years | 4th Quintile 19–20 years | 5th Quintile >20 years | ||
| Demographic factors | ||||||
| Age (years), median (IQR) | 27 (21–34) | 25 (20–32) | 25 (21–32) | 28 (23–34) | 30 (25–35) | <0.001* |
| Less than high school education | 86% | 76% | 71% | 67% | 62% | <0.001 |
| Zulu speaking at home | 96% | 95% | 95% | 92% | 92% | 0.037 |
| Religion—Christian | 91% | 90% | 90% | 90% | 91% | 0.827 |
| Single/not living with a regular sex partner | 88% | 89% | 87% | 85% | 81% | <0.001 |
| Sexual risk behaviours | ||||||
| Using condom (as current contraception) | 45% | 42% | 47% | 45% | 46% | 0.347 |
| Using any contraception | 77% | 77% | 77% | 80% | 78% | 0.784 |
| At least four lifetime sex partners | 39% | 29% | 25% | 18% | 14% | <0.001 |
| Biological risk factors | ||||||
| HIV prevalence | 48% | 43% | 41% | 37% | 33% | <0.001 |
| STI prevalence | 20% | 15% | 14% | 13% | 12% | <0.001 |
| HSV prevalence | 79% | 74% | 71% | 70% | 68% | <0.001 |
↵* Kruskal–Wallis test was used.
HSV, herpes simplex virus; STI, sexually transmitted infection.