Patterns of age mixing and sexually transmitted infections.

Age mixing is an important indicator of sexually transmitted infection (STI) prevalence in partner pools. We use the 1995 National Survey of Family Growth (NSFG), a nationally representative sample of reproductive-age American women, to assess the extent of age mixing and to examine the association between age mixing and STI history. Almost half (48%) of the women in our sample report partnerships with much older or younger men. The likelihood of an STI diagnosis or receipt of STI care (test or treatment) increases as the age difference increases among adolescents. Women in their mid-to-late 20s with much younger partners report receipt of STI care more often than other women. Report of an STI diagnosis is more common among older women with much younger partners than among others of their age. Age-mixing information may be helpful for screening initiatives and targeting interventions aimed at decreasing STI rates, their sequelae, and STI transmission.