Background: Treatment of cervical intraepithelial neoplasia grade 3 (CIN 3) removes or destroys part of the cervix and might subsequently influence pregnancy outcomes.
Objective: To investigate pregnancy outcomes in women diagnosed with CIN 3.
Design: Population- and sibling-matched cohort study.
Setting: Sweden, 1973 to 2018.
Participants: The general population comparison included 78 450 singletons born to women diagnosed with CIN 3 and 784 500 matched singletons born to women in the general population who had no CIN 3 diagnosis; the sibling comparison included 23 199 singletons born to women diagnosed with CIN 3 and 28 135 singletons born to their sisters without a CIN 3 diagnosis.
Measurements: Preterm birth, including spontaneous or iatrogenic preterm birth; infection-related outcomes, including chorioamnionitis and infant sepsis; and early neonatal death, defined as death during the first week after birth.
Results: Compared with the matched general population, women previously diagnosed with CIN 3 were more likely to have a preterm birth, especially extremely preterm (22 to 28 weeks; odds ratio [OR], 3.00 [95% CI, 2.69 to 3.34]) or spontaneous preterm (OR, 2.12 [CI, 2.05 to 2.20]); infection-related outcomes, including chorioamnionitis (OR, 3.23 [CI, 2.89 to 3.62]) and infant sepsis (OR, 1.72 [CI, 1.60 to 1.86]); or early neonatal death (OR, 1.83 [CI, 1.61 to 2.09]). Sibling comparison analyses rendered largely similar results. Over time, the risk difference attenuated for all outcomes and disappeared for early neonatal death.
Limitation: Lack of data on CIN 3 treatment and spontaneous abortion.
Conclusion: History of CIN 3 is associated with adverse pregnancy outcomes even after accounting for familial factors. Decreasing risk estimates over time suggest that adverse pregnancy outcomes among women diagnosed with CIN 3 may be minimized by improving treatment methods.
Primary funding source: The Swedish Research Council, the Swedish Cancer Society, and the Swedish Research Council for Health, Working Life and Welfare.