The association of post-conization pregnancy with subsequent cervical lesions: evidence from a nationwide cohort in Sweden

Abstract Background Women who have undergone cervical conization may still experience subsequent pregnancies and delivery. However, it remains unknown whether pregnancy, associated with immune tolerance, might increase the risk of subsequent cervical lesions. This study aims to address this knowledge gap by utilizing the nationwide Swedish registers. Methods A total of 60,895 women diagnosed with cervical intraepithelial neoplasia in Sweden between January 1997 and December 2017 and treated with conization were identified through the Swedish National Patient Register and followed for subsequent cervical lesions. Time-dependent Cox regression was used to examine the association of post-conization pregnancies with subsequent cervical lesions. Results Among the 60,895 women who underwent conization in Sweden, 15,200 (25%) had post-conization pregnancies and showed a higher incidence of subsequent cervical lesions (hazard ratio = 1.32, 95% confidence interval = 1.13–1.53) compared to women without pregnancies. The increased risk of subsequent cervical lesions was observed only in women who had a pregnancy within 3 years after conization (adjusted hazard ratio = 1.39, 95% confidence interval = 1.19–1.63). Conclusions Our study demonstrates that post-conization pregnancies are associated with a higher risk of subsequent cervical lesions compared to women without pregnancies. The risk was particularly significant in women who had a pregnancy within 3 years after conization, suggesting that those who become pregnant within 3 years after conization will need close clinical monitoring.