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

TL;DR

Women who become pregnant after cervical conization have a higher risk of developing cervical lesions, especially if the pregnancy occurs within 3 years of the procedure.

Contribution

This study is the first to show a link between post-conization pregnancies and increased cervical lesion risk using a large nationwide cohort.

Findings

Post-conization pregnancies were associated with a 32% higher risk of subsequent cervical lesions.

The increased risk was significant only for pregnancies occurring within 3 years after conization.

Women with pregnancies within 3 years had a 39% higher risk of cervical lesions compared to non-pregnant women.

Abstract

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.

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.

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).

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.

The online version contains supplementary material available at 10.1186/s12916-025-04541-w.

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