title: Sex-specific risks for pediatric onset among patients with Crohn's disease.
abstract: OBJECTIVE
  Increases in the incidence of pediatric Crohn's disease might reflect increases in incidence for onset at all ages or diagnostic improvement. Alternatively, there might be etiologic differences between adult and pediatric-onset disease with different risks for pediatric disease. Differences in sex ratio between adult and pediatric disease suggest etiologic differences might exist and also suggest differences in sex-specific susceptibility during childhood. This study seeks to identify whether factors previously associated with overall risk of Crohn's disease (number of siblings and maternal age) are associated with pediatric as opposed to adult onset among patients with Crohn's disease and whether these associations vary by sex.
  
  
  METHODS
  A nested case-control study of patients with Crohn's disease was designed to compare pediatric with adult-onset disease. The participants were all patients with Crohn's disease in the Swedish Inpatient Register born between 1960 and 1998; 46.6% of the 4826 patients were male.
  
  
  RESULTS
  A notable association between mother's age at pregnancy and pediatric Crohn's disease was observed in female but not male patients. Compared with those whose mothers were younger than 21 years, female patients with older mothers, coded into ordered 5-year age categories, were at a higher risk of pediatric disease with adjusted odds ratios (95% confidence intervals) of 1.42 (0.85-2.37), 2.08 (1.19-3.66), 3.50 (1.83-6.69), 3.02 (1.35-6.75), and 12.64 (3.63-43.98). No statistically significant independent associations were observed for father's age or number of siblings.
  
  
  CONCLUSIONS
  Females might be more susceptible or more often exposed to factors associated with older maternal age at pregnancy that increase their risk of pediatric-onset Crohn's disease.
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine, Karolinska Hospital M9:01, Karolinska Institutet, SE-171 76 Stockholm, Sweden. Scott.Montgomery@medks.ki.se
authors.forename: Scott M
authors.initials: SM
authors.lastname: Montgomery
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wakefield
authors.forename: Anders
authors.initials: A
authors.lastname: Ekbom
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D016022:Case-Control Studies; D002648:Child; D002669:Child Welfare; D002675:Child, Preschool; D003424:Crohn Disease / Q000453:epidemiology*; D005192:Family Health; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008423:Maternal Age; D008875:Middle Aged; D012042:Registries; D018570:Risk Assessment; D012737:Sex Factors; D013223:Statistics as Topic; D013548:Sweden / Q000453:epidemiology