title: Evidence that intrauterine and postnatal androgens affect the development of pyloric stenosis.
abstract: BACKGROUND
  It is rather well established that the causal antecedents of pyloric stenosis (PS) contain both genetic and environmental factors. However, in spite of substantial quantities of epidemiological data, no widespread environmental causal agent has yet been established. There have been recent extensions of our knowledge of the endocrine consequences of fetal growth restriction and of the endocrine determinants of sex ratio. It seemed worth reviewing the epidemiological data on PS in the light of these new developments to see whether this would provide a basis for a plausible hypothesis on these suspected environmental causes of PS.
  
  
  RESULTS
  The search terms "pyloric stenosis" and ("epidemiology" or "risk factors") were combined on the Ovid Medline data base for the years 1966 onwards. The data from the resulting papers were augmented by notes occasioned by almost daily reading at the Library of the Royal Society of Medicine (London) for the past 25 years. (Electronic data retrieval systems do not access incidentally recorded data such as sib sex ratios).
  
  
  CONCLUSIONS
  It is hypothesized that high intrauterine and early postnatal androgen levels constitute an environmental cause of PS.
authors.affiliation: Galton Laboratory, University College London, Wolfson House, 4 Stephenson Way, London NW1 2HE, United Kingdom.
authors.forename: William H
authors.initials: WH
authors.lastname: James
mesh_terms: D000728:Androgens / Q000502:physiology*; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D006801:Humans; D015994:Incidence; D016239:MEDLINE; D008297:Male; D011247:Pregnancy; D011707:Pyloric Stenosis / Q000196:embryology / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D012744:Sex Ratio
chemical_list: D000728:Androgens