Parity as a cofactor for high-grade cervical disease among women with persistent human papillomavirus infection: a 13-year follow-up

Background: Several environmental factors have been associated with increased risks for cervical cancer. We examined whether reproductive history, contraceptive use, or sexual behaviour increase the risk for cervical intraepithelial neoplasia grade 3 or worse (CIN3+) among women with persistent human papillomavirus (HPV) infection. Methods: A population-based cohort of women participated in a personal interview and underwent a gynaecological examination at which cervical specimens were obtained for HPV DNA testing. Follow-up information (similar to 13 years) on cervical lesions was obtained from the Danish Pathology Data Bank. Women who had a high-risk HPV infection comprised the overall study population (n = 1353). A subgroup of women with persistent high-risk HPV infection (n = 312) was identified. Hazard ratios (HRs) for a diagnosis of CIN3+ and the corresponding 95% confidence intervals (CIs) were calculated. Results: Women with persistent HPV infection who had given birth had a significantly increased risk for CIN3+ (HR = 1.78; 95% CI: 1.07-2.94). No association was found with pregnancy, use of intrauterine devices, or sexual behaviour. Based on small numbers, women with persistent HPV infection had a decreased risk for CIN3+ with any use of oral contraceptives (HR = 0.54; 95% CI: 0.29-1.00). Conclusion: Childbirth increases the risk for subsequent CIN3+ among women with persistent HPV infection.