Menstrual, reproductive, and contraceptive factors associated with cervical cancer in women aged ≤35 years: an individually matched case-control study.

Objective: This study aims to investigate the associations of menstrual, reproductive, and contraceptive characteristics with early-onset cervical cancer among women aged ≤35 years. Methods: A hospital-based, individually matched case-control study was conducted at West China Second University Hospital from January 2022 to December 2024. A total of 300 women aged ≤35 years and with histologically confirmed cervical cancer were individually matched 1:1 to 300 screening controls within 0.5 years of age and 7 days of recruitment. Menstrual, reproductive, and contraceptive histories accrued up to 90 days before the index data were collected through standardized interviews and medical record reviews. Separate exposure-specific conditional logistic regression models stratified by matched pair were adjusted for prespecified sociodemographic, behavioral, screening-related, infection-related, and current high-risk human papillomavirus (hrHPV) covariates. The model samples ranged from 189 to 277 matched pairs. Exploratory subgroup analyses assessed effect modification. Results: In the fully adjusted model, menstrual period duration was associated with early-onset cervical cancer, with evidence of nonlinearity ( Conclusions: Selected menstrual, reproductive, and contraceptive characteristics were associated with early-onset cervical cancer after adjustment for measured confounders and current hrHPV status.