title: [Physical development and puberty of Polish 13 year old adolescents in the first decade of 21st century. Current status and secular trend of growth and maturation in the last 30 years].
abstract: OBJECTIVE
  1. Current physical status and selected pubertal features were assessed in Polish 13-year old adolescents, in urban and rural areas. 2. Dynamics and secular trends of body height, mass and body mass index in 1980-2008 were analyzed.
  
  
  METHODS
  The study was conducted in 2008 in prospective cohort of 605 children (305 girls and 300 boys), who had been observed in the neonatal period, later at age of 3 years and now at age of 13 years. 49% adolescents were from urban and 51% from rural area. For secular trend analyses comparisons of the age and sex-specific means of body height, mass and BMI from 2008 with previous data from 1980, 1999 and 2005 in 13-year old were carried out. Similar comparison was made concerning average age at menarche by using previous probit analysis to determine average age at menarche during the last 3 decades.
  
  
  RESULTS
  Mean values of anthropometric features in adolescents were a little higher in 13-yrs old living in urban than rural area, but were statistically insignificant. Two thirds of examined 13-year-old girls already had their first period (menarche), statistically more often urban living girls (p = 0,017). The median age at menarche for entire group of 13-year-old girls estimated by means of Kaplan-Meier analysis was 12.77 years. The girls from urban areas had their first menses earlier than their rural living peers (12.65 and 12.88 years, p = 0.01). There were no statistically significant differences in urban and rural boys concerning age of appearance of facial hair. There are increases of mean height and weight values during the period of 30 years in 13-year-olds (2.51 cm and 2.2 kg for girls and 5.51 cm and 5.08 kg for boys) and BMI 0.21 kg/m3 and 0.75 kg/m2 for girls and boys. The average age of menarche was almost the same as in Warsaw girls in 1986 and 1996.
  
  
  CONCLUSIONS
  1. The study confirmed a reduction of differences in somatic development between 13-years olds in rural and urban areas. 2. Difference in mean age at menarche is still observed, they show earlier maturation in urban girls (about 2 months earlier than in rural girls). 3. Positive secular trend in height in Polish 13-year-olds is observed during the last 3 decades. 4. The mean age at menarche in Polish girls stabilized at 12.77 years in the last decade.
authors.affiliation: Zakład Ochrony i Promocji Zdrowia Dzieci i Młodziezy, Instytut Matki i Dziecka w Warszawie. anna.oblacinska@imid.med.pl
authors.forename: Anna
authors.initials: A
authors.lastname: Oblacińska
authors.forename: Maria
authors.initials: M
authors.lastname: Jodkowska
authors.forename: Izabela
authors.initials: I
authors.lastname: Tabak
authors.forename: Krystyna
authors.initials: K
authors.lastname: Mikiel-Kostyra
authors.forename: Iwona
authors.initials: I
authors.lastname: Palczewska
mesh_terms: D000293:Adolescent / Q000502:physiology*; D000886:Anthropometry; D001827:Body Height / Q000502:physiology; D015992:Body Mass Index; D002648:Child; D005260:Female; D006128:Growth / Q000502:physiology*; D006801:Humans; D008297:Male; D008572:Menarche / Q000502:physiology; D011044:Poland; D011627:Puberty / Q000502:physiology*; D012423:Rural Health; D012741:Sexual Maturation / Q000502:physiology; D014504:Urban Health