title: Are incidence and severity of clubfoot related to the season of birth?
abstract: BACKGROUND
  This study was designed to determine whether the occurrence of clubfoot follows a seasonal pattern in neonates from eastern and south-eastern China and to speculate the potential etiology of clubfoot.
  
  
  METHODS
  We reviewed 239 neonates with clubfeet during a period of 4 years as well as the monthly neonatal population of the Sixth National Population Census. Seasonal variations in terms of month of birth and severity were analyzed.
  
  
  RESULTS
  The incidence of clubfoot in neonates from eastern and south-eastern China showed seasonal variations, and the incidence was higher in autumn with a reference to the average birth rate in this corresponding area. No significant difference was found in severity of clubfoot.
  
  
  CONCLUSIONS
  This seasonal pattern is of significant value to further understanding the etiology and pathogenesis of clubfoot in the corresponding area of China.
authors.affiliation: Department of Pediatric Orthopedics, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
authors.forename: Da-Hang
authors.initials: DH
authors.lastname: Zhao
authors.affiliation: Department of Pediatric Critical Care Medicine, Shanghai, China.
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Rao
authors.affiliation: Department of Pediatric Orthopedics, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China. orthzl@126.com.
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Pediatric Orthopedics, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Pediatric Orthopedics, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
authors.forename: Jian-Lin
authors.initials: JL
authors.lastname: Liu
authors.affiliation: Department of Pediatric Orthopedics, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
authors.forename: Zhen-Kai
authors.initials: ZK
authors.lastname: Wu
authors.affiliation: Department of Rehabilitation Medicine, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Du
authors.affiliation: Department of Rehabilitation Medicine, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Yang
mesh_terms: D002681:China / Q000453:epidemiology; D003025:Clubfoot / Q000175:diagnosis* / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008297:Male; D012189:Retrospective Studies; D018570:Risk Assessment; D012621:Seasons; D017678:Sex Distribution
keywords: clubfoot; etiology; seasonality