Objectives. To investigate the association between loop electrosurgical excision procedure (LEEP) and other potential risk factors, and subsequent preterm delivery (<37 weeks), using data from a large cohort study of Danish women. Methods. The Danish prospective cohort study was initiated in 1991, with the original aim of investigating the role of human papillomavirus in the natural history of cervical neoplasia. The study included 11,088 women aged 20–29. The cohort was invited for 2 follow-up examinations in 1993–1995 and 1999–2000, respectively. At all 3 examinations, the women answered questions about a number of different lifestyle variables. We assessed the relationship between preterm delivery and potential risk factors, such as previous LEEP treatments, smoking during pregnancy, age, parity and previous preterm delivery. The cohort was followed until 2004, through linkages with the nationwide Pathology Data Bank and the Medical Birth Registry. Results. Of the 14,982 deliveries in the cohort during follow up, 542 were preterm (21–37 weeks). Among deliveries with no previous LEEP, 3.5% ended as a preterm delivery, whereas this applied to 6.6% among deliveries following a LEEP, yielding a significantly increased risk of preterm birth after LEEP (OR = 1.8; 95% CI: 1.1–2.9). The strongest risk factor for preterm delivery was a previous preterm delivery (OR = 2.3; 95% CI: 1.4–3.7). Other significant risk factors were smoking during pregnancy and low educational status. Conclusion. Our study showed an almost 2-fold increase in the risk of preterm delivery after LEEP treatment. Thus, women in their reproductive age should be informed about the increased risk of preterm delivery, if treated with LEEP.