title: Association of prematurity with the development of infantile hypertrophic pyloric stenosis.
abstract: BACKGROUND
  Infantile hypertrophic pyloric stenosis (IHPS) has several known risk factors. The association between prematurity and IHPS and the timeline of presentation are poorly defined. Our aim was to evaluate the associations between IHPS and prematurity.
  
  
  METHODS
  We performed a retrospective cohort study of 1,074,236 children born between June 2001 and April 2012 in the US Military Health System. IHPS cases and gestational ages (GA) were identified using billing codes. Additional risk factors for IHPS were controlled for in a multivariable logistic regression model.
  
  
  RESULTS
  The incidence of IHPS was 2.99 per 1,000 in preterm infants and 2.25 per 1,000 in full term (relative risk (RR) = 1.33, 95% confidence interval (CI) 1.16-1.54). The adjusted odds ratio for prematurity was 1.26 (95% CI 1.08-1.46). The median (interquartile range (IQR)) chronological age at presentation was 40 d (30-56) in preterm infants vs. 33 d (26-45) in full term (P < 0.001). Median postmenstrual age at presentation was 42 wk in preterm infants (40-42) vs. 45 wk (44-46) in full term (P < 0.001).
  
  
  CONCLUSIONS
  Prematurity is associated with IHPS. Premature infants develop IHPS at a later chronological age, but earlier postmenstrual age, than term infants. Providers should have an increased concern for IHPS development in premature infants.
authors.affiliation: Department of Pediatrics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Stark
authors.affiliation: Department of Pediatrics, Walter Reed National Military Medical Center, Bethesda, Maryland.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Rogers
authors.affiliation: 1] Department of Pediatrics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland [2] Department of Pediatrics, Walter Reed National Military Medical Center, Bethesda, Maryland.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Eberly
authors.affiliation: 1] Department of Pediatrics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland [2] Department of Pediatrics, Walter Reed National Military Medical Center, Bethesda, Maryland.
authors.forename: Cade M
authors.identifier: 0000000345436804
authors.initials: CM
authors.lastname: Nylund
mesh_terms: D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D046248:Pyloric Stenosis, Hypertrophic / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies