Background. To investigate the effect of cervical laser conisation (CLC) or loop electrosurgical excision procedure (LEEP) on the outcome of subsequent pregnancies. Methods. Multi-centre, retrospective, case-control study, which included a cohort of 742 women, who, after treatment with LEEP or CLC, gave birth or suffered second trimester miscarriage. Control women (n = 742) were extracted from the respective hospital birth registries and matched by age and parity. Outcome measures were perinatal mortality, length of gestation, birth weight and preterm premature rupture of membranes (pPROM). Results. There was no significant difference in perinatal mortality among women treated with LCL or LEEP compared to controls, 6/742 versus 2/742: odds ratio (OR) = 3.1 (95% CI: 0.6–15.2). Excluding second trimester miscarriages, ORs for giving birth before week 37, 32 and 28 after conisation compared to the controls were 3.4 (95% CI: 2.3–5.1), 4.6 (95% CI: 1.7–12.5), and 12.4 (95% CI: 1.6–96.1), respectively, after adjusting for smoking habits during pregnancy, marital status and educational level. Adjusted ORs of birth weight <2,500, <1,500 and <1,000 g after conisation compared to controls were 3.9 (95% CI: 2.4–6.3), 4.4 (95% CI: 1.5–13.6), and 10.4 (95% CI: 1.3–82.2), respectively. The adjusted OR for pPROM was 10.5 (95% CI: 3.7–29.5). Conclusion. Treatment by CLC and LEEP increases the risk of preterm delivery, low birth weight and pPROM in subsequent pregnancies.