Background: We evaluated the safety and efficacy of CO2 laser conization in pregnant women with cervical intraepithelial neoplasia 3/carcinoma in situ (CIN3/CIS) or microinvasive carcinoma (MIC). Objectives: A total of 49 pregnant women with biopsy-proven CIN3/CIS (30 patients) or MIC (19 patients) were studied.Methods: Retrospective analysis based on clinical records. Results: Median age and median week of gestation were 31 years (range: 22–39) and 17 weeks (range: 7–33), respectively. The median length of cervix resected by conization, median duration of surgery and median blood loss were 14 mm (range: 5–23), 20 min (range: 7–35) and 78 ml (range: 10–797), respectively. One biopsy-proven CIN3/CIS patient was diagnosed with Federation of Gynecology and Obstetrics (FIGO) Ia2 and 3 biopsy-proven MIC patients were diagnosed with FIGO Ib1 based on conization specimens. A total of 35 patients could be followed until delivery, of which 27 (77.1%) patients delivered transvaginally. Although 8 patients (22.9%) had a cesarean section and 6 patients (17.1%) delivered preterm, no conization-related obstetric complications were observed. Conclusion: Since it results in few obstetric complications, CO2 laser conization within 20 mm of length can be considered a safe procedure for pregnant women.