Pregnancy incidence and outcome before and after cervical intraepithelial neoplasia: a retrospective cohort study

We performed a retrospective cohort study of 3530 women treated for cervical intraepithelial neoplasia (CIN) in Helsinki University Central Hospital, Finland, to investigate whether CIN treatment itself affects pregnancy incidence and outcome. We estimated the incidence of live births, miscarriages, extrauterine pregnancies, molar pregnancies, and termination of pregnancies (TOPs) before and after CIN treatment using nationwide registers. Women were followed up until death, emigration, sterilization, or the end of 2004. The comparison of incidence of pregnancy outcomes before and after the treatment was estimated by calculating hazard ratios (HRs) with conditional Poisson regression. After 76,162 woman-years of follow-up, the incidence of any pregnancy remained constant over CIN-treatment, HR 1.02 and 95% confidence interval (CI) 0.97–1.08, but the incidence of the first pregnancy was significantly elevated after treatment, HR 1.13, and 95% CI 1.03–1.23. The incidence of live births was significantly elevated after treatment, HR 1.08 and 95% CI 1.01–1.15. Incidence of miscarriages, TOPs, extrauterine pregnancies, and molar pregnancies was not elevated. TOPs was significantly increased in the first pregnancy, HR 1.40, 95% CI 1.15–1.72 and after treatment by the loop electrosurgical excision procedure (LEEP), HR 1.36, 95% CI 1.15–1.60. CIN treatment did not reduce pregnancy incidence and women had more live births after than before CIN treatment. TOPs was more common in the first pregnancy or after treatment by LEEP. We encourage research on the psychosocial consequences of CIN treatment also in other countries and settings.