Objective To determine if large loop excision of the transformation zone affects subsequent fertility and pregnancy outcome.
Design A case-control study.
Setting A teaching hospital serving a regional population.
Subjects One thousand women who had undergone large loop excision of the transformation zone (LLETZ) for the treatment of cervical intraepithelial neoplasia (CIN) between 1989 and 1991. Two controls were matched for each of the 149 women who had a singleton pregnancy progressing beyond 20 weeks of gestation following treatment, with regard to age, parity, height, husband's or partner's social class and smoking habits to account for common independent risk factors for adverse obstetric outcome and cervical intraepithelial neoplasia.
Main outcome measures Intention to conceive, number of pregnancies, gestation, low birthweight, mean birthweight, mode of delivery, and duration of labour.
Results Out of a cohort of 1000 women who underwent LLETZ for the treatment of CIN, 653 women replied to a postal questionnaire. When asked up to 54 months after treatment, 130 women (19.9%) had become pregnant and 47 (7.2%) had tried to become pregnant. A total of 199 pregnancies from 178 women was identified from the cohort of women.
For the 149 women from the case cohort, the mean birthweight was 3380 g compared with 3373 g in the control group (P= 0.88). The incidence of low birthweight in pregnancies progressing to at least 37 weeks of gestation was 3.1% in the treated group, compared with 3.2% in the control group (P= 098). Following LLETZ, 94% of deliveries were preterm (< 37 weeks of gestation), compared with 50% in the control group (P= 0.12). There was no significant difference in mean gestation, mode of delivery, indication for caesarean section or duration of labour between the women who had undergone LLETZ and the controls.
Conclusion When socio-epidemiological factors associated with the development of cervical intraepithelial neoplasia are controlled for, LLETZ does not appear to exert an independent adverse effect on subsequent pregnancy outcome.