title: [Male predominance and birth weight in hypertrophic pyloric stenosis].
abstract: BACKGROUND
  Infantile hypertrophic pyloric stenosis (IHPS), although fairly frequent, is still an enigmatic disease. Its incidence is increased among relatives of a case and among infants of male sex (M) and of high birthweight. The purpose of this paper is to analyze the pattern of IHPS M predominance according to birthweight (BW).
  
  
  METHODS
  115 consecutive cases charts of IHPS were reviewed and stratified by gender and BW rank (500 g each, beginning at 1,500 g and ending at 3,500 g). Statistical analysis was done by means of chi square and comparation of proportions tests.
  
  
  RESULTS
  M predominance was not observed in IHPS patients with a BW of 2,500 g or less (n = 11, 6M). Female infants (F) did not increase their number of cases as the BW rose, but M did, reaching an 8.8 to 1 M to F ratio among those with a BW of 3,500 9 or more (p < 0.005). The proportion of M with a BW of 3,000 g or more was significantly higher than in F (0.826 vs. 0.521, p < 0.005).
  
  
  CONCLUSIONS
  In IHPS, the excess of M cases, which is responsible of the M/F disparity, is present only among newborns with a BW of 3,000 g or more. The disease does not show this relation to BW in F.
authors.affiliation: Hospital de Especialidades 1, Centro Médico Nacional Noroeste, Instituto Mexicano del Seguro Social, Ciudad Obregón, Sonora, México. Illalex@infosel.net.mx
authors.forename: A V
authors.initials: AV
authors.lastname: Gómez-Alcalá
mesh_terms: D001724:Birth Weight; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D006984:Hypertrophy; D015994:Incidence; D008297:Male; D008800:Mexico / Q000453:epidemiology; D011707:Pyloric Stenosis / Q000453:epidemiology*; D012737:Sex Factors