Table 1

Characteristics of children enrolled in the Observational Research in Childhood Infectious Diseases study

Characteristic (n=158 unless stated)Frequency (%) or mean (±SD)
Sex (male)75 (47.5%)
Gestational age (weeks)39.8 (±1.3)
Birth weight (g)3530.8 (±430.4)
  Vaginal107 (67.7%)
Birth order (maternal)
  First born106 (67.1%)
Parental mean age
  Mother (years) (n=157)31.8 (±4.6)
Family history of asthma or eczema
  Mother50 (31.6%)
  Father44 (27.8%)
  Sibling15 (9.5%)
  First-degree relative with asthma or eczema83 (52.5%)
Smoke exposure at birth
  Mother (n=156)5 (3.2%)
  Other householder (n=155)*17 (11.0%)
Maternal educational status (n=157)
  Primary school5 (3.2%)
  High school15 (9.6%)
  Diploma/certificate38 (24.2%)
  University or higher university degree99 (63.1%)
Household income (n=155)†
  Lowest quarter0
  Lower quarter17 (11.0%)
  Higher quarter52 (33.5%)
  Highest quarter86 (55.5%)
Child immunisation status to 18 months (n=154)‡
  Fully immunised141 (91.6%)
Exclusive breast feeding
  At birth (n=149)142 (95.3%)
  At 3 months (n=142)97 (68.3%)
  At 6 months (n=133)5 (3.8%)
  At 6 months (n=133)33 (24.8%)
  At 9 months (n=123)48 (39.0%)
  At 12 months (n=115)72 (62.6%)
  At 15 months (n=110)87 (79.1%)
  • *Includes two single parent households.

  • †Income categories based on Australian Bureau of Statistics income quartiles (quartile 1: <$A26 000; quartile 2: $A26 000–$A67 499; quartile 3: $A67 500–$A114 999; quartile 4: ≥$A115 000).

  • ‡11/154 (7.1%) infants did not receive a full course of rotavirus vaccines because they presented for immunisation outside of required age limits; 2 children had chickenpox diagnosed before the varicella vaccine could be administered at the scheduled age of 18 months, but were up-to-date for all other vaccines; another 2 children withdrew early and information was unavailable on their later immunisations. Influenza vaccines are not part of the national Australian infant immunisation schedule. Only 7 children received the influenza vaccine in the first 2 years of life.