title: Multistate study of the epidemiology of clubfoot.
abstract: BACKGROUND
  Although clubfoot is a common birth defect, with a prevalence of approximately 1 per 1000 livebirths, the etiology of clubfoot remains largely unknown. Studies of the prevalence and risk factors for clubfoot in the United States have previously been limited to specific states. The purpose of this study was to pool data from several birth defects surveillance programs to better estimate the prevalence of clubfoot and investigate its risk factors.
  
  
  METHODS
  The 10 population-based birth defects surveillance programs that participated in this study ascertained 6139 cases of clubfoot from 2001 through 2005. A random sample of 10 controls per case, matched on year and state of birth, was selected from birth certificates. Data on infant and maternal risk factors were collected from birth certificates. Prevalence was calculated by pooling the state-specific data. Conditional logistic regression was used to investigate the association between risk factors and clubfoot.
  
  
  RESULTS
  The overall prevalence of clubfoot was 1.29 per 1000 livebirths; 1.38 among non-Hispanic whites, 1.30 among Hispanics, and 1.14 among non-Hispanic blacks or African Americans. Maternal age, parity, education, and marital status were significantly associated with clubfoot. Maternal smoking and diabetes also showed significant associations. Several of these observed associations were consistent between surveillance programs.
  
  
  CONCLUSIONS
  We estimated the prevalence of clubfoot using data from several birth defects programs, representing one-quarter of all births in the United States. Our findings underline the importance of birth defects surveillance programs and their utility in monitoring population-based prevalence and investigating risk factors.
authors.affiliation: National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. gwf5@cdc.gov
authors.forename: Samantha E
authors.initials: SE
authors.lastname: Parker
authors.forename: Cara T
authors.initials: CT
authors.lastname: Mai
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Strickland
authors.forename: Richard S
authors.initials: RS
authors.lastname: Olney
authors.forename: Russel
authors.initials: R
authors.lastname: Rickard
authors.forename: Lisa
authors.initials: L
authors.lastname: Marengo
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: S Shahrukh
authors.initials: SS
authors.lastname: Hashmi
authors.forename: Robert E
authors.initials: RE
authors.lastname: Meyer
mesh_terms: D000328:Adult; D001719:Birth Certificates; D003025:Clubfoot / Q000453:epidemiology*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D011159:Population Surveillance; D015995:Prevalence; D014481:United States / Q000453:epidemiology