Odds of STIs and multiple sexual partners associated with 1-year increase in duration of premarital sex in Moshi women, Tanzania, 2002–2003. The adjusted analyses control for the effect of age, education, religion, tribe and condom use in the previous 12 months. Moreover, besides these variables, the adjusted analyses of STIs (HIV-1, HSV-2, other STIs, symptoms STIs) control for the effect of number of sexual partners.