- The purpose of the present study was to examine obstetric outcome of patients following conization and specifically the risk for preterm delivery (PTD). A population-based study was performed comparing pregnancies in women following conization with those who had not undergone the procedure. Stratified analysis, using a multiple logistic regression model was performed to control for confounders. Out of 104,670 deliveries, 53 women (0.05%) had undergone conization. Most conizations were performed using loop electrosurgical excision procedure (LEEP). Using multivariable analysis, the following conditions were significantly associated with conization: advanced maternal age, PTD before the 34th week, low birth weight, and cervical incompetence with cerclage. Higher rates of perinatal mortality were noted in pregnancies of women with conization, but after controlling for PTD, the association lost its significance. The risk of PTD <34 weeks was significantly higher than the comparison group (OR 7.73 95% CI 3.77-15.85, p < 0.001). This association remained significant after controlling for confounders, such as cervical incompetence, smoking, maternal age, birth order and year of delivery (OR 2.8 95% CI 1.3-6.1, p = 0.008). When comparing pregnancy outcomes of women with and without cerclage due to cervical incompetence, no significant differences were documented. A clear association exists between conization and PTD before the 34th week. This association persists after controlling for variables considered to coexist with PTD. Careful surveillance is required in pregnancies of women following conization for early detection of preterm contractions and PTD.