title: Do men become infertile after having sexually transmitted urethritis? An epidemiologic examination.
abstract: OBJECTIVE
  To critically assess the possibility that gonorrhea or chlamydia causes male infertility.
  
  
  METHODS
  Comprehensive literature review structured to evaluate the epidemiologic tenets for causality, including biologic plausibility, strength of association, dose response, consistency, temporality, and treatment effect.
  
  
  RESULTS
  It is biologically plausible that gonorrhea and/or chlamydia could cause male infertility. There is clinical and pathologic evidence linking these pathogens to urethritis, linking urethritis to epididymo-orchitis, and linking epididymo-orchitis to infertility. Retrospective epidemiologic results also support an association between chlamydia serologies and male infertility, which in most of these small studies does not reach the level of statistical significance. However, there is no consistent epidemiologic evidence that these pathogens alter sperm characteristics. We discuss the methodologic limitations of previous epidemiologic studies and suggest strategies for future research.
  
  
  CONCLUSIONS
  Whether gonorrhea and/or chlamydia cause male infertility is currently unclear. Sound methodologic research strategies must be applied to future studies.
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pennsylvania, USA.
authors.forename: R B
authors.initials: RB
authors.lastname: Ness
authors.forename: N
authors.initials: N
authors.lastname: Markovic
authors.forename: C L
authors.initials: CL
authors.lastname: Carlson
authors.forename: M T
authors.initials: MT
authors.lastname: Coughlin
mesh_terms: D002690:Chlamydia Infections; D005260:Female; D006069:Gonorrhea; D006801:Humans; D007248:Infertility, Male / Q000453:epidemiology* / Q000209:etiology / Q000382:microbiology*; D008297:Male; D012749:Sexually Transmitted Diseases / Q000382:microbiology*; D014526:Urethritis / Q000382:microbiology*