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) |
| Delivery | |
| Vaginal | 107 (67.7%) |
| Birth order (maternal) | |
| First born | 106 (67.1%) |
| Parental mean age | |
| Mother (years) (n=157) | 31.8 (±4.6) |
| Family history of asthma or eczema | |
| Mother | 50 (31.6%) |
| Father | 44 (27.8%) |
| Sibling | 15 (9.5%) |
| First-degree relative with asthma or eczema | 83 (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 school | 5 (3.2%) |
| High school | 15 (9.6%) |
| Diploma/certificate | 38 (24.2%) |
| University or higher university degree | 99 (63.1%) |
| Household income (n=155)† | |
| Lowest quarter | 0 |
| Lower quarter | 17 (11.0%) |
| Higher quarter | 52 (33.5%) |
| Highest quarter | 86 (55.5%) |
| Child immunisation status to 18 months (n=154)‡ | |
| Fully immunised | 141 (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%) |
| Childcare | |
| 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.