title: Effect of prenatal indoor pet exposure on the trajectory of total IgE levels in early childhood.
abstract: BACKGROUND
  The presence of pets in a home during the prenatal period and during early infancy has been associated with a lower prevalence of allergic sensitization and total IgE levels in middle childhood. No studies have examined the effect of pet exposure in a population-based cohort by using multiple early-life measures of serum total IgE.
  
  
  OBJECTIVE
  We sought to examine within-individual longitudinal trends in total IgE levels during early childhood and assess the effect of indoor prenatal pet exposure on those trends. Also, we sought to use a statistical method that was flexible enough to allow and account for unequally spaced study contacts and missing data.
  
  
  METHODS
  Using the population-based Wayne County Health, Environment, Allergy and Asthma Longitudinal Study birth cohort (62% African American), we analyzed 1187 infants with 1 to 4 measurements of total IgE collected from birth to 2 years of age. Effects of pet exposure on the shape and trajectory of IgE levels were assessed by using a multilevel longitudinal model, accommodating repeated measures, missing data, and the precise time points of data collection.
  
  
  RESULTS
  The best-fit shape to the trajectory of IgE levels was nonlinear, with an accelerated increase before 6 months. Total IgE levels were lower across the entire early-life period when there was prenatal indoor pet exposure (P < .001). This effect was statistically significantly stronger in children delivered by means of cesarean section versus those delivered vaginally (P < .001 and P < .06, respectively) and in those born to non-African American (P < .001) versus African American (P < .3) mothers.
  
  
  CONCLUSIONS
  Pet exposure and delivery mode might be markers of infant exposure to distinct microbiomes. The effect of exposures might vary by race, suggesting a differential effect by ancestry.
authors.affiliation: Department of Public Health Sciences, Henry Ford Hospital, Detroit, MI 48202, USA. shavsta1@hfhs.org
authors.forename: Suzanne
authors.initials: S
authors.lastname: Havstad
authors.forename: Ganesa
authors.initials: G
authors.lastname: Wegienka
authors.forename: Edward M
authors.initials: EM
authors.lastname: Zoratti
authors.forename: Susan V
authors.initials: SV
authors.lastname: Lynch
authors.forename: Homer A
authors.initials: HA
authors.lastname: Boushey
authors.forename: Charlotte
authors.initials: C
authors.lastname: Nicholas
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Ownby
authors.forename: Christine Cole
authors.initials: CC
authors.lastname: Johnson
mesh_terms: D000328:Adult; D001741:Black or African American; D000818:Animals; D002675:Child, Preschool; D004781:Environmental Exposure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood* / Q000276:immunology*; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D018448:Models, Immunological; D057805:Pets; D015995:Prevalence; D013997:Time Factors; D014481:United States / Q000453:epidemiology
chemical_list: D007073:Immunoglobulin E