title: Association between prior appendectomy and/or tonsillectomy in women and subsequent pregnancy rate: a cohort study.
abstract: OBJECTIVE
  To study pregnancy rates after appendectomy and/or tonsillectomy.
  
  
  METHODS
  Population-based cohort study using the United Kingdom (U.K.) primary health care-based Clinical Practice Research Datalink (CPRD).
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Female patients who underwent appendectomy, tonsillectomy, or both from 1987 to 2012 and appropriate comparators.
  
  
  METHODS
  Timed follow-up until first pregnancy after surgery. The association between prior surgery and subsequent pregnancy was determined with the use of Cox regression models.
  
  
  METHODS
  Pregnancy rate and time to first pregnancy after surgery.
  
  
  RESULTS
  The analyses included 54,675 appendectomy-only patients, 112,607 tonsillectomy-only patients, 10,340 patients who had both appendectomy and tonsillectomy, and 355,244 comparators matched for exact age and practice from the rest of female patients in the database. There were 29,732 (54.4%), 60,078 (53.4%), and 6,169 (59.7%) pregnancies in the appendectomy-only, tonsillectomy-only, and both appendectomy tonsillectomy cohorts, respectively versus 155,079 (43.7%) in the comparator cohort during a mean follow-up of 14.7 ± 9.7 years. Adjusted hazard ratios (HRs) for subsequent birth rates were 1.34 (95% confidence interval [CI] 1.32-1.35), 1.49 (95% CI 1.48-1.51), and 1.43 (95% CI 1.39-1.47), respectively. Time to pregnancy was shortest after both appendectomy and tonsillectomy followed by appendectomy only and then tonsillectomy only compared with the rest of the population.
  
  
  CONCLUSIONS
  Appendectomy and/or tonsillectomy was associated with increased subsequent pregnancy rates and shorter time to pregnancy. The effect of the surgical procedures on the pregnancy outcome was cumulative.
authors.affiliation: Department of Practice and Policy, School of Pharmacy, University College London, London.
authors.forename: Li
authors.initials: L
authors.lastname: Wei
authors.affiliation: Medicines Monitoring Unit, Medical Research Institute, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland.
authors.forename: Thomas
authors.initials: T
authors.lastname: MacDonald
authors.affiliation: Department of Surgery, Ninewells Hospital and Medical School, Dundee, United Kingdom. Electronic address: s.m.shimi@dundee.ac.uk.
authors.forename: Sami
authors.initials: S
authors.lastname: Shimi
mesh_terms: D000293:Adolescent; D001062:Appendectomy; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008423:Maternal Age; D015999:Multivariate Analysis; D011247:Pregnancy; D018873:Pregnancy Rate; D016016:Proportional Hazards Models; D013997:Time Factors; D061685:Time-to-Pregnancy; D014068:Tonsillectomy; D006113:United Kingdom; D055815:Young Adult
keywords: Appendectomy; pregnancy rate; time to pregnancy; tonsillectomy