Table 1.

General Characteristics of the Study Population, Stratified for Parental History of Allergic Disease

CharacteristicBoth Parents Nonallergic (n = 1700)Mother Allergic (n = 677)Father Allergic (n = 710)Both Parents Allergic (n = 331)Total (n = 3418)
Male gender (%)50.852.752.347.451.1
Maternal age (mean y ± standard deviation)30.4 (3.9)30.1 (3.7)30.5 (3.8)30.0 (4.1)30.3 (3.9)
Duration of pregnancy
 37–40 wk (%)44.443.047.748.545.2
 >40 wk (%)51.052.248.445.750.2
 <37 wk (%)4.64.83.85.94.6
Birth weight (mean g ± standard deviation)3512 (539)3502 (570)3527 (518)3452 (398)3507 (547)
Season of birth
 Winter17.120.819.419.018.5
 Spring25.124.422.520.824.0
 Summer31.423.631.127.829.5
 Fall26.431.226.932.328.0
Method of feeding
 Only breastfeeding at 3 mo of age30.231.632.736.031.5
 Breastfeeding and formula at 3 mo16.817.417.215.416.9
 Only formula feeding at 3 mo53.051.050.148.651.6
% with at least 1 older sibling52.148.251.747.450.8
Siblings with allergic disease (% of total)*22.330.228.730.626.0
Form of child care
 No child care (%)35.136.331.834.434.6
 Child care small group (%)41.840.841.041.441.4
 Child care large group (%)23.122.927.224.224.0
Smoking mother during pregnancy
 No smoking (%)79.683.382.883.481.4
 Only first trimester (%)4.43.84.54.84.3
 Whole pregnancy (%)16.012.912.711.814.3
Both parents low level of education(%)6.56.65.66.96.4
  • *  Allergic disease in siblings defined as having a history of asthma, eczema, hay fever, or other inhalant allergies.

  •  No child care = no form of child care at all; small child care = regularly cared for by relatives or foster parents and contact with small numbers of children other than their siblings; large child care = child care centers, usually 10 or more children.

  •  Both parents have a maximum of 4 years high school education.