title: Geographic analysis of individual and environmental risk factors for hypospadias births.
abstract: BACKGROUND
  Hypospadias is a relatively common birth defect affecting the male urinary tract. We explored the etiology of hypospadias by examining its spatial distribution in North Carolina and the spatial clustering of residuals from individual and environmental risk factors.
  
  
  METHODS
  We used data collected by the North Carolina Birth Defects Monitoring Program from 2003 to 2005 to estimate local Moran's I statistics to identify geographic clustering of overall and severe hypospadias, using 995 overall cases and 16,013 controls. We conducted logistic regression and local Moran's I statistics on standardized residuals to consider the contribution of individual variables (maternal age, maternal race/ethnicity, maternal education, smoking, parity, and diabetes) and environmental variables (block group land cover) to this clustering.
  
  
  RESULTS
  Local Moran's I statistics indicated significant clustering of overall and severe hypospadias in eastern central North Carolina. Spatial clustering of hypospadias persisted when controlling for individual factors, but diminished somewhat when controlling for environmental factors. In adjusted models, maternal residence in a block group with more than 5% crop cover was associated with overall hypospadias (odds ratio = 1.22; 95% confidence interval = 1.04-1.43); that is living in a block group with greater than 5% crop cover was associated with a 22% increase in the odds of having a baby with hypospadias. Land cover was not associated with severe hypospadias.
  
  
  CONCLUSIONS
  This study illustrates the potential contribution of mapping in generating hypotheses about disease etiology. Results suggest that environmental factors including proximity to agriculture may play some role in the spatial distribution of hypospadias. Birth Defects Research (Part A) 100:887-894, 2014. © 2014 Wiley Periodicals, Inc.
authors.affiliation: Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Winston
authors.forename: Robert E
authors.initials: RE
authors.lastname: Meyer
authors.forename: Michael E
authors.initials: ME
authors.lastname: Emch
mesh_terms: D000328:Adult; D000367:Age Factors; D000383:Agriculture; D044383:Black People; D016022:Case-Control Studies; D016000:Cluster Analysis; D004522:Educational Status; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D007021:Hypospadias / Q000453:epidemiology* / Q000208:ethnology / Q000209:etiology; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D009657:North Carolina / Q000453:epidemiology; D016017:Odds Ratio; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology* / Q000208:ethnology / Q000209:etiology; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000503:physiopathology; D044465:White People; D001741:Black or African American
keywords: Moran's I; North Carolina; agriculture; hypospadias; spatial clustering