title: Seasonal variations of cerebral palsy births in northeastern Poland.
abstract: BACKGROUND
  The objective of this report was to examine the seasonal variations on the incidence of cerebral palsy (CP) in Podlasie province, Poland in a retrospective case-control study.
  
  
  METHODS
  Data were obtained from the Department of Pediatric Neurology and Rehabilitation. Selected babies were all born between January 1, 1990 and December 31, 1999; 212 children (116 boys, 96 girls) with CP were included in the study. We applied Cosinor analysis to examine the seasonality of CP births.
  
  
  RESULTS
  The highest number of CP births occurred in spring and the lowest in winter, with intermediate values in summer and autumn. This seasonal pattern was significant for spring vs. winter. The peaks in CP births occurred in May and August. The lowest number of CP births occurred in February and December. We also demonstrated seasonal variation in CP births in girls and boys and Apgar score. Peaks in CP births in boys were noted in May and October and Apgar score in May and December, respectively. No significant relationship between mean temperature and Apgar score, low birthweight and asphyxia was found.
  
  
  CONCLUSIONS
  These data suggest the seasonal patterns of CP births. Further studies should be performed with larger numbers of patients.
authors.affiliation: Department of Pediatric Neurology and Rehabilitation, Medical University of Bialystok, Bialystok, Poland. kulak@hot.pl
authors.forename: Wojciech
authors.initials: W
authors.lastname: Kulak
authors.forename: Wojciech
authors.initials: W
authors.lastname: Kulal
authors.forename: Wojciech
authors.initials: W
authors.lastname: Sobaniec
mesh_terms: D001723:Birth Rate; D002547:Cerebral Palsy / Q000453:epidemiology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008297:Male; D011044:Poland / Q000453:epidemiology; D012621:Seasons; D014798:Vital Statistics