title: Sensitization does not develop in utero.
abstract: BACKGROUND
  Intrauterine sensitization has been suggested to play a role in the development of atopic disease in children, and this has led to current guidelines recommending allergen avoidance during pregnancy.
  
  
  OBJECTIVE
  To investigate the relevance of allergen-specific IgE in cord blood to sensitization in early infancy and the origin of such IgE.
  
  
  METHODS
  Inhalant and food allergen-specific IgE in cord blood was analyzed and compared with specific IgE in infant blood at 6 months of age and in parental blood. Cord blood IgA was measured to detect maternal blood contamination of cord blood.
  
  
  RESULTS
  Allergen-specific IgE, primarily against inhalant allergens, was detected in 14% of cord blood samples. However, corresponding specific IgE was not found in infant blood at 6 months of age. Specific IgE in cord blood completely matched specific IgE in maternal blood with respect to allergen specificity, level of specific IgE, and ratio of total IgE/specific IgE. Finally, there was a correlation between specific IgE and IgA in cord blood.
  
  
  CONCLUSIONS
  Allergen-specific IgE in cord blood does not reflect intrauterine sensitization but seems to be the result of transfer of maternal IgE to the fetus.
authors.affiliation: Danish Pediatric Asthma Center, Department of Pediatrics, Copenhagen University Hospital, Copenhagen, Denmark. kb@copsac.dk
authors.forename: Klaus
authors.initials: K
authors.lastname: Bønnelykke
authors.forename: Christian Bressen
authors.initials: CB
authors.lastname: Pipper
authors.forename: Hans
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D000485:Allergens / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005312:Fetal Blood / Q000276:immunology*; D005512:Food Hypersensitivity / Q000209:etiology / Q000276:immunology; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000097:blood / Q000276:immunology*; D007070:Immunoglobulin A / Q000097:blood; D007073:Immunoglobulin E / Q000097:blood*; D007223:Infant; D007231:Infant, Newborn; D019570:Inhalation Exposure / Q000009:adverse effects; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000097:blood / Q000276:immunology*
chemical_list: D000485:Allergens; D007070:Immunoglobulin A; D007073:Immunoglobulin E