title: Time trends and geographic variations in the prevalence of hypospadias in China.
abstract: BACKGROUND
  Little is known about the main epidemiologic characteristics of hypospadias prevalence in China. We investigated the time trends and geographic variations in the prevalence of hypospadias in China from 1996 to 2008.
  
  
  METHODS
  Data were retrieved from the hospital-based birth defects monitoring system in China from 1996 to 2008. We used prevalence ratios (PRs) to describe the difference in prevalence of hypospadias between urban and rural areas, as well as among different regions. Poisson regression was used to explore the long time trend for the prevalence of hypospadias and its regional disparity.
  
  
  RESULTS
  The prevalences of hypospadias for isolated anomalies, multiple anomalies, and overall cases were 7.64, 1.39, and 9.03 per 10,000 births, respectively. The national PRs (urban vs. rural) of hypospadias for overall and isolated cases were 1.25 (95% confidence interval [CI], 1.16-1.35) and 1.27 (95% CI, 1.17-1.38), respectively. The highest prevalence (12.10 per 10,000 births) was observed in the eastern region. A positive correlation was found between the prevalence of hypospadias and maternal age (p < 0.01). The average annual increase of 7.43% (95% CI, 5.52-9.38%) was observed in the overall prevalence of hypospadias in China; it was 5.28% (95% CI, 4.16-6.43%) in urban areas, 9.79% (95% CI, 7.72-11.90%) in rural areas, 9.08% (95% CI, 6.36-11.86%) in the eastern region, 4.76% (95% CI, 2.93-6.62%) in the central region, and 6.57% (95% CI, 4.44-8.74%) in the western region.
  
  
  CONCLUSIONS
  The increasing trends and differences of hypospadias prevalence by urban-rural classification and geographical location suggest that environmental exposure and maternal age might have a critical role in the development of hypospadias.
authors.affiliation: National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.
authors.forename: Yuehua
authors.initials: Y
authors.lastname: Li
authors.forename: Meng
authors.initials: M
authors.lastname: Mao
authors.forename: Li
authors.initials: L
authors.lastname: Dai
authors.forename: Kesheng
authors.initials: K
authors.lastname: Li
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Li
authors.forename: Guangxuan
authors.initials: G
authors.lastname: Zhou
authors.forename: Yanping
authors.initials: Y
authors.lastname: Wang
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.forename: Chunhua
authors.initials: C
authors.lastname: He
authors.forename: Juan
authors.initials: J
authors.lastname: Liang
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
mesh_terms: D002681:China / Q000453:epidemiology; D000013:Congenital Abnormalities / Q000453:epidemiology; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007021:Hypospadias / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D008499:Medical Records; D011159:Population Surveillance / Q000379:methods; D015995:Prevalence; D012424:Rural Population / Q000706:statistics & numerical data*; D013997:Time Factors; D014505:Urban Population / Q000706:statistics & numerical data*