Objective: To estimate the risk for preterm delivery and obstetric complications in women with prior cold-knife conization.
Methods: In a retrospective study, we compared 76 deliveries of 65 women with prior cold-knife conization with the remaining 29,711 singleton deliveries at our institution between 1992 and 2002.
Results: We found significant shorter duration of pregnancies in the conization group. Delivery prior to 37 weeks was found in 22.4% (n = 17) of the conization group and in 6.6% (n = 1961) of the controls (OR = 4.07 [2.22-7.10], P < 0.001). Preterm premature rupture of the membranes was found in 17.1% (n = 13) of the conization group and in 2.6% (n = 775) of the controls (OR = 7.70 [3.87-14.21], P < 0.001). Birth weight less than 2500 g was found in 18.4% (n = 14) of the conization group and in 7.7% (n = 2280) of the controls (OR = 2.72 [1.40-4.92], P = 0.002). Overall, birth weight in the conization group was not significantly lower (median 3147 g vs. 3287 g, P = 0.115). Cervical tears were found more frequently in the conization group (8.8% [n = 6] vs. 1.3% [n = 236], OR = 7.53 [2.63-17.57], P < 0.001). There was no difference in mode of delivery, duration of labor, head circumference, chorioamnionitis and use of oxytocin.
Conclusion: Cold-knife conization is a risk factor for preterm birth and preterm premature rupture of the membranes and seems to be a risk factor for cervical tears.