Distribution of selected characteristics of 763 parent-child pairs
| Variable | No (%) or mean (SD) |
| Baseline characteristics | |
| Maternal age (years) | 30.0 (4.0) |
| Gestation (weeks) | 17.7 (6.7) |
| Residential municipality | |
| Neyagawa City | 457 (59.9) |
| Other than Neyagawa City | 306 (40.1) |
| Family income (% yen/year) | |
| <4 000 000 | 211 (27.7) |
| 4 000 000–5 999 999 | 313 (41.0) |
| 6 000 000+ | 239 (31.3) |
| Maternal education (% years) | |
| <13 | 212 (27.8) |
| 13–14 | 329 (43.1) |
| ≥15 | 222 (29.1) |
| Paternal education (% years) | |
| <13 | 289 (37.9) |
| 13–14 | 127 (16.6) |
| ≥15 | 347 (45.5) |
| Maternal history of asthma (%) | 80 (10.5) |
| Maternal history of atopic eczema (%) | 120 (15.7) |
| Maternal history of allergic rhinitis (%) | 256 (33.6) |
| Paternal history of asthma (%) | 64 (8.4) |
| Paternal history of atopic eczema (%) | 72 (9.4) |
| Paternal history of allergic rhinitis (%) | 143 (18.7) |
| Changes in diet in the previous month (%) | |
| None or seldom | 212 (27.8) |
| Slight | 336 (44.0) |
| Substantial | 215 (28.2) |
| Season when data were collected (%) | |
| Spring | 241 (31.6) |
| Summer | 127 (16.6) |
| Fall | 167 (21.9) |
| Winter | 228 (29.9) |
| Characteristics at postnatal assessment | |
| Maternal smoking during pregnancy (%) | 97 (12.7) |
| Baby’s older siblings (% ≥1) | 381 (49.9) |
| Baby’s sex (% male) | 403 (52.8) |
| Baby’s birth weight (g) | 3071.0 (415.5) |
| Household smoking in same room as infant | 195 (25.6) |
| Breastfeeding duration (% months) | |
| <6 | 189 (24.8) |
| ≥6 | 574 (75.2) |
| Time of delivery before third survey (% months) | |
| 16–19 | 263 (34.5) |
| 20 | 370 (48.5) |
| 21–24 | 130 (17.0) |