Birth outcomes following treatment for precancerous changes to the cervix: a population-based record linkage study

Abstract

Objective: To examine whether treatments for precancerous changes to the cervix are associated with adverse birth outcomes in subsequent pregnancies.

Design: Population-based retrospective cohort study using electronic linkage of data from the Welsh cervical screening programme and a national routine child health database.

Setting: Wales.

Population: A total of 174,325 women aged 20-39 years who received cervical screening between April 2001 and March 2004.

Methods: Logistic regression was used to compare the odds of each birth outcome between women who had negative cervical smears and women who received either colposcopy ± punch biopsy only or colposcopy and excisional or ablative treatments, adjusted for confounding factors (e.g. age, social deprivation and smoking).

Main outcome measures: Preterm birth (before 37, 32 and 28 weeks of gestation), and low birthweight (<2500 g).

Results: Compared with women who had negative cervical smears, the odds ratio for preterm birth (<37 weeks) was significantly increased in women who had colposcopy only (adjusted odds ratio 1.54, 95% CI 1.32-1.80) and single excisional treatment (adjusted odds ratio 1.77, 95% CI 1.47-2.13). Similar results were observed for preterm birth at <32 weeks of gestation. There was no increased risk of preterm birth or low birthweight for women who had treatment compared with women who had colposcopy only.

Conclusion: Women who were referred for colposcopy had an increased risk of preterm births regardless of whether or not they received treatment to the cervix. This increased risk could be the result of common risk factors for abnormal smears and preterm birth.