title: Development of nocturnal urinary control in Chinese children younger than 8 years old.
abstract: OBJECTIVE
  To estimate the development of nocturnal urinary control (NUC) with age in Chinese children younger than 8 years of age using cross-sectional and retrospective surveys.
  
  
  METHODS
  We used a cross-sectional survey of 4754 children (1 to 8 years old), a retrospective investigation of 2745 children younger than 9 years old, and an anonymous questionnaire of 8222 children 9 to 18 years old . The children without NUC were subdivided into infant (1 to 3 years old), preschool age (4 to 6 years old), and primary school (7 to 8 years old) groups.
  
  
  RESULTS
  The response rate to the cross-sectional and retrospective surveys was 90% and 89%, respectively. In the cross-sectional survey, the prevalence of children attaining NUC was 52% for those younger than 2 years of age, 76% for those aged 2 to 3 years, and 93% at age 8. Girls were more likely than boys to acquire NUC earlier. In the retrospective survey, the prevalence of children attaining NUC before age 2 was 17% and was 72% for those aged 2 to 3 years, and 98% by age 8. The proportion of nonmonosymptomatic bedwettings in children without NUC was 14%. Arousal difficulty and a positive family history were found in 67% and 11% of children with nocturnal wetting, respectively. The severity of bedwetting and arousal difficulty was significantly greater in infants than in preschool and school-age children.
  
  
  CONCLUSIONS
  The results from the cross-sectional and retrospective surveys showed that the most important period of attaining NUC is 2 to 3 years of age. Nearly 90% of children attained NUC by the age of 5.
authors.affiliation: Department of Pediatric Surgery, Pediatric Urodynamic Centre, First Affiliated Hospital of Zhengzhou University, Zhengzhou City, Henan, China. jgwen@zzu.edu.cn
authors.forename: Jian Guo
authors.initials: JG
authors.lastname: Wen
authors.forename: Qing Wei
authors.initials: QW
authors.lastname: Wang
authors.forename: Jian Jun
authors.initials: JJ
authors.lastname: Wen
authors.forename: Jing
authors.initials: J
authors.lastname: Su
authors.forename: Yue
authors.initials: Y
authors.lastname: Chen
authors.forename: Kui
authors.initials: K
authors.lastname: Liu
authors.forename: He Ying
authors.initials: HY
authors.lastname: Yang
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D002681:China; D003430:Cross-Sectional Studies; D006801:Humans; D007223:Infant; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D014554:Urination / Q000502:physiology*