title: Is the increased risk of preterm birth following excision for cervical intraepithelial neoplasia restricted to the first birth post treatment?
abstract: OBJECTIVE
  To explore whether the increased risk of preterm birth following treatment for cervical disease is limited to the first birth following colposcopy.
  
  
  METHODS
  Nested case-control study.
  
  
  METHODS
  Twelve NHS hospitals in England.
  
  
  METHODS
  All nonmultiple births from women selected as cases or controls from a cohort of women with both colposcopy and a hospital birth. Cases had a preterm (20-36 weeks of gestation) birth. Controls had a term birth (38-42 weeks) and no preterm.
  
  
  METHODS
  Obstetric, colposcopy and pathology details were obtained.
  
  
  METHODS
  Adjusted odds ratio of preterm birth in first and second or subsequent births following treatment for cervical disease.
  
  
  RESULTS
  A total of 2798 births (1021 preterm) from 2001 women were included in the analysis. The risk of preterm birth increased with increasing depth of treatment among first births post treatment [trend per category increase in depth, categories <10 mm, 10-14 mm, 15-19 mm, ≥20 mm: odds ratio (OR) 1.23, 95% confidence interval (95% CI) 1.12-1.36, P < 0.001] and among second and subsequent births post treatment (trend OR 1.34, 95% CI 1.15-1.56, P < 0.001). No trend was observed among births before colposcopy (OR 0.98, 95% CI 0.83-1.16, P = 0.855). The absolute risk of a preterm birth following deep treatments (≥15 mm) was 6.5% among births before colposcopy, 18.9% among first births and 17.2% among second and subsequent births post treatment. Risk of preterm birth (once depth was accounted for) did not differ when comparing first births post colposcopy with second and subsequent births post colposcopy (adjusted OR 1.15, 95% CI 0.89-1.49).
  
  
  CONCLUSIONS
  The increased risk of preterm birth following treatment for cervical disease is not restricted to the first birth post colposcopy; it remains for second and subsequent births. These results suggest that once a woman has a deep treatment she remains at higher risk of a preterm birth throughout her reproductive life.
authors: Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Bart's & The London School of Medicine, Queen Mary University of London, London, UK.
authors: A
authors: A
authors: Castañon
authors: Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Bart's & The London School of Medicine, Queen Mary University of London, London, UK.
authors: R
authors: R
authors: Landy
authors: Institute for Women's Health UCL, London, UK.
authors: P
authors: P
authors: Brocklehurst
authors: Department of Gynaecology, Royal Free Hampstead NHS Trust, London, UK.
authors: H
authors: H
authors: Evans
authors: Institute for Women's Health UCL, London, UK.
authors: D
authors: D
authors: Peebles
authors: Division of Cellular Pathology, Barts Health, London, UK.
authors: N
authors: N
authors: Singh
authors: Department of Gynaecology, Royal Free Hampstead NHS Trust, London, UK.
authors: P
authors: P
authors: Walker
authors: Public Health England/Director NHS Cancer Screening Programmes, Sheffield, UK.
authors: J
authors: J
authors: Patnick
authors: Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Bart's & The London School of Medicine, Queen Mary University of London, London, UK.
authors: P
authors: P
authors: Sasieni
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003127:Colposcopy / Q000009:adverse effects; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016017:Odds Ratio; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology* / Q000209:etiology; D012307:Risk Factors; D002583:Uterine Cervical Neoplasms / Q000601:surgery*; D002578:Uterine Cervical Dysplasia / Q000601:surgery*
keywords: Cervical intraepithelial neoplasia; conisation; large loop excision of the transformation zone; preterm delivery