Cervical intraepithelial neoplasia (CIN) is a precancerous lesion common in reproductive-aged women. Many women will go on to pregnancies after treatment for CIN and there is concern about treatment methods and adverse obstetric outcomes, including preterm birth. A large register-based Scandinavian study examined the pregnancy outcomes of more than 4500 women who received loop electrosurgical excision procedure (LEEP, LLETZ) treatment for CIN1 between 1997 and 2009, and their 31,021 subsequent deliveries.1 Within this group of women, there was increase in the rate of preterm birth (before 37 weeks gestation) when comparing pre- and post-LEEP treatment (odds ratios 1.47, 95% confidence interval 1.05–2.06). There was no significant increase if women received a diagnosis of CIN1, but did not have a LEEP procedure (odds ratios 0.90, 95% confidence interval 0.71–1.13). In comparison with other women delivering in the same catchment in the study period, those who received a diagnosis of CIN1, but did not have a LEEP procedure, did not have an increased risk of preterm labour (odds ratios 0.95, 95% confidence interval 0.76–1.21), while those who had a LEEP procedure did have an increased risk of preterm labour (odds ratios 1.45, 95% CI 1.02–1.92).1

A 2017 Cochrane review analysed treatment of any grade of CIN and early grade IA1 cervical cancer. Studies included treatment observation, excision or ablative treatments.2 The analysis included data from over six million pregnancies, with 65,000 women having received treatment. Women who had treatment were at increased overall risk of preterm birth at less than 37 weeks, compared to women who had not received treatment (10.7% vs 5.4%, RR 1.75, 95% CI 1.57 to 1.96). They also had higher rates of delivery before 34 and 28 weeks. There was a higher rate of preterm delivery with excisional rather than ablative techniques, and increased rates with increased depth of excision for repeat treatment.3 These studies reinforce the knowledge that excision treatment of cervical disease increases the risk of preterm labour in subsequent pregnancies. Appropriate observation or ablative procedures may be considered as an alternative in some women.