Abstract： Objective To investigate the effect of cervical knife conization (CKC) or loop electrical excision procedure (LEEP) on the outcome of subsequent pregnancies and mode of deliveries. Methods A retrospective case-control study including 228 women after treatment with LEEP or CKC for cervical intraepithelial neoplasia (CIN) Ⅱ -Ⅲ who gave birth in the First Affiliated Hospital of Sun Yat-sen University and He-xian Memorial Hospital of Pangyu from January 2004 to January 2010 was performed. Patients (n = 228) without cervical surgical history were randomly extracted from the respective hospitals birth registries as controls and were matched by age, gestation,parity and income. The information including gestational age, premature rupture of membranes (PROM), type of deliveries and birth weight of the two groups were collected.Results The gestational age of women treated with conization was (268.3±26.2) d, longer than that of the women without surgery (279.4±25.3) d (t=4.60, P＜0.01). The incidence of preterm birth was 18.0％(41/228) and 4.4％ (10/228) (x2 = 21.22, P＜ 0. 05). The incidence of PROM was higher in conizationgroup (10.1％, 23/228) than that (1.3％, 3/228) in control group (x2=16.32, P＜0. 05). Risk for PROM was almost eight fold (OR=8. 42, 95％CI: 2.49-28.44) higher in conization group. Cesarean section rate was higher in conization group (69.3 ％ ) than in control group (39.0 ％ )(x2=42.06, P＜0. 01). The gestational age of women treated with LEEP was longer than those treated with CKC[(269.8±24.6) d vs (260.2± 26.5) d, t= 4. 01, P＜0.01]. The incidence of preterm birth was 13. 1％ (22/168) and 31.6％ (19/60) (x2 = 10. 34, P＜0. 05). The mean birth weight of women with LEEP was heavier than that with CKC[(3358.5 ±812.2) g vs (3295.9 ±832.6) g, t=3.08, P＜0. 01]. The incidence of PROM (7.1％, 12/168) of woman with CKC was higher than that (1.3％, 11/60) of women with LEEP (x2 =6.10, P＜0.05). Conclusions Conization might increase the incidence of preterm delivery and preterm PROM. LEEP showed less adverse effect on the outcome of subsequent pregnancies than CKC, and was preferred for primigravida, and the risk of treatment should be informed in advance.