title: Seasonality of congenital anomalies in Europe.
abstract: BACKGROUND
  This study describes seasonality of congenital anomalies in Europe to provide a baseline against which to assess the impact of specific time varying exposures such as the H1N1 pandemic influenza, and to provide a comprehensive and recent picture of seasonality and its possible relation to etiologic factors.
  
  
  METHODS
  Data on births conceived in 2000 to 2008 were extracted from 20 European Surveillance for Congenital Anomalies population-based congenital anomaly registries in 14 European countries. We performed Poisson regression analysis encompassing sine and cosine terms to investigate seasonality of 65,764 nonchromosomal and 12,682 chromosomal congenital anomalies covering 3.3 million births. Analysis was performed by estimated month of conception. Analyses were performed for 86 congenital anomaly subgroups, including a combined subgroup of congenital anomalies previously associated with influenza.
  
  
  RESULTS
  We detected statistically significant seasonality in prevalence of anomalies previously associated with influenza, but the conception peak was in June (2.4% excess). We also detected seasonality in congenital cataract (April conceptions, 27%), hip dislocation and/or dysplasia (April, 12%), congenital hydronephrosis (July, 12%), urinary defects (July, 5%), and situs inversus (December, 36%), but not for nonchromosomal anomalies combined, chromosomal anomalies combined, or other anomalies analyzed.
  
  
  CONCLUSIONS
  We have confirmed previously described seasonality for congenital cataract and hip dislocation and/or dysplasia, and found seasonality for congenital hydronephrosis and situs inversus which have not previously been studied. We did not find evidence of seasonality for several anomalies which had previously been found to be seasonal. Influenza does not appear to be an important factor in the seasonality of congenital anomalies.
authors.affiliation: Institute of Nursing Research/School of Nursing, University of Ulster, Jordanstown Campus, Newtownabbey, United Kingdom.
authors.forename: Johannes Michiel
authors.initials: JM
authors.lastname: Luteijn
authors.forename: Helen
authors.initials: H
authors.lastname: Dolk
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Addor
authors.forename: Larraitz
authors.initials: L
authors.lastname: Arriola
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Barisic
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Bianchi
authors.forename: Elisa
authors.initials: E
authors.lastname: Calzolari
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Draper
authors.forename: Ester
authors.initials: E
authors.lastname: Garne
authors.forename: Miriam
authors.initials: M
authors.lastname: Gatt
authors.forename: Martin
authors.initials: M
authors.lastname: Haeusler
authors.forename: Babak
authors.initials: B
authors.lastname: Khoshnood
authors.forename: Bob
authors.initials: B
authors.lastname: McDonnell
authors.forename: Vera
authors.initials: V
authors.lastname: Nelen
authors.forename: Mary
authors.initials: M
authors.lastname: O'Mahony
authors.forename: Carmel
authors.initials: C
authors.lastname: Mullaney
authors.forename: Annette
authors.initials: A
authors.lastname: Queisser-Luft
authors.forename: Judith
authors.initials: J
authors.lastname: Rankin
authors.forename: David
authors.initials: D
authors.lastname: Tucker
authors.forename: Christine
authors.initials: C
authors.lastname: Verellen-Dumoulin
authors.forename: Hermien
authors.initials: H
authors.lastname: de Walle
authors.forename: Lyubov
authors.initials: L
authors.lastname: Yevtushok
mesh_terms: D000013:Congenital Abnormalities / Q000453:epidemiology*; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012042:Registries; D012189:Retrospective Studies; D012621:Seasons
keywords: Influenza, Human; Seasonal Variation; abnormalities, congenital; epidemiology; public health