title: The height-, weight-, and BMI-for-age of Polish school-aged children and adolescents relative to international and local growth references.
abstract: BACKGROUND
  The growth of children is an indicator of health and society's wellbeing. Growth references are useful in monitoring a child's growth, which is a very important part of child care. Poland's growth references are not updated regularly. Although several growth reference ranges have been developed in Poland over recent years, sampling was restricted to urban populations of major cities. The aim of this study was to assess how well Polish children match with, or diverge from, regional charts and to compare them with international growth references.
  
  
  METHODS
  Four Polish and two international (WHO 2007 and USCDC2000) growth references were used to calculate the height, weight and BMI z-scores in a recent, large, population-representative sample of school-aged children and adolescents in Poland. The distributions of z-scores were analysed with descriptive and inferential statistical methods.
  
  
  RESULTS
  Mean height z-scores calculated with the use of the WHO 2007 and USCDC2000 references were positive and significantly different from zero over the entire age range. The mean height z-score was closest to zero in the Poznan reference for boys (0.05) and Warszawa reference for girls (0.01). Median weight z-scores were positive under all weight references over the entire age range with only the exception of 18-year-old girls' weight z-score calculated relative to USCDC2000. Median BMI z-scores were positive in males in early childhood, decreasing with age. In the case of girls, the median BMI z-score calculated using WHO 2007 and USCDC2000 was close to zero in early childhood, decreased in adolescents and reached minimum values at age 18 years. Median BMI z-scores calculated with the use of the Lodz reference fluctuated between 0.05 and 0.2 over the studied age range.
  
  
  CONCLUSIONS
  In this contemporary sample of Polish school-aged children, distributions of height, weight and BMI differed from those of children from the international growth references. These differences should be considered when using the references. There exist certain limitations to the analysis of height, weight, and BMI z-scores when Polish regional references are used.
authors.affiliation: Public Health Division, The Children's Memorial Health Institute, Warsaw, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Kulaga
authors.forename: Mieczysław
authors.initials: M
authors.lastname: Litwin
authors.forename: Marcin
authors.initials: M
authors.lastname: Tkaczyk
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Rózdzyńska
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Barwicka
authors.forename: Aneta
authors.initials: A
authors.lastname: Grajda
authors.forename: Anna
authors.initials: A
authors.lastname: Swiader
authors.forename: Beata
authors.initials: B
authors.lastname: Gurzkowska
authors.forename: Ewelina
authors.initials: E
authors.lastname: Napieralska
authors.forename: Huiqi
authors.initials: H
authors.lastname: Pan
mesh_terms: D000293:Adolescent; D001823:Body Composition / Q000502:physiology; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002657:Child Development / Q000502:physiology; D003625:Data Collection; D005260:Female; D057238:Growth Charts; D006801:Humans; D008297:Male; D011044:Poland; D018709:Statistics, Nonparametric