Figure 1.

Prevalence odds ratios for human papillomavirus*. (a) The association between cervical HPV infection and age at first sexual intercourse stratified by lifetime number of sexual partners. Reference group: ≥21 years of age at first sexual intercourse. (b) The association between cervical HPV infection and lifetime number of sexual partners stratified by age at first sexual intercourse. Reference group: 1 sexual partner. P < 0.001 for association for each age stratum. *Model adjusted for age, Autonomous Community, country of birth, marital status, level of education, smoking habits, and history of genital warts.