title: The impact of parental history on children's risk of asthma: a study based on the National Health and Nutrition Examination Survey-III.
abstract: OBJECTIVE
  This study aimed to examine the separate effects of maternal and paternal history on the onset of asthma in children and evaluate the relationship between age of asthma onset in parents and risk of asthma in their children.
  
  
  METHODS
  We used data from the third National Health and Nutrition Examination Survey. We developed new continuous standardized scores for survey data to quantify parental history that incorporated both the occurrence of asthma and the age at onset, and associated these scores with asthma risk in the children. The association analysis was adjusted for sex and obesity status.
  
  
  RESULTS
  Children with maternal history have elevated asthma risk (hazard ratio of 3.71, 95% CI: 1.19-11.60) than those without, and those whose mothers had earlier age of onset have increased risk of asthma compared to those whose mothers had later age of onset. On the contrary, paternal history had a relatively smaller effect that may be only detectable in larger samples (hazard ratio of 2.17, 95% CI: 0.69-6.79).
  
  
  CONCLUSIONS
  Maternal asthma history was strongly associated with the onset of asthma in the second generation, and children whose mother had an earlier age of onset had an increased risk of 3.71. For an approximately 10-year decrease in mother's age at onset of asthma, the risk of asthma for the offspring increased by 1.37-fold. Using our new risk scores led to smaller standard errors and thus more precise estimates than using a binary indicator.
authors.affiliation: Department of Biostatistics and Epidemiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Rengyi
authors.initials: R
authors.lastname: Xu
authors.affiliation: Division of Neonatology, Perelman School of Medicine at the University of Pennsylvania and The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
authors.forename: Sara B
authors.initials: SB
authors.lastname: DeMauro
authors.affiliation: Department of Biostatistics and Epidemiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Feng
keywords: asthma risk; family data; maternal history; parental history; survey