Table 1. Distribution of Baseline Patient Characteristics in the Derivation and Validation Cohort (Number(percentage)).
| Derivation cohort (n = 1,227) | Validation cohort (n = 1,194) | |
| Male gender | 676 (55.1%) | 659 (55.2%) |
| Gestational age (wk) | 34 | 34 |
| 32 | 115 (9.4%) | 124 (10.4%) |
| 33 | 296 (24.1%) | 240 (20.1%) |
| 34 | 371 (30.2%) | 429 (35.9%) |
| 35 | 445 (36.3%) | 401 (33.6%) |
| Birth Weight (g) (Mean(SD)) | 2214 (452) | 2225 (427) |
| Multiple pregnancy | 426 (34.7%) | 422 (35.3%) |
| Caesarean section | 409 (33.3%) | 436 (36.5%) |
| Continuous positive airway pressure | 166 (13.5%) | 217 (18.2%) |
| Mechanical ventilation* | 46 (3.7%) | 35 (2.9%) |
| Born Aug 14 th to Dec 1 st | 324 (26.4%) | 496 (41.5%) |
| Breastfeeding** less than 2months or not # | 416 (33.9%) | 376 (31.5%) |
| Presence of siblings | 504 (41.1%) | 463 (38.8%) |
| Atopy in 1st degree family member | 642 (52.3%) | 729 (61.1%) |
| Fur bearing pets | 571 (46.5%) | 548 (45.9%) |
| Maternal smoking during pregancy | 164 (13.4%) | 136 (11.4%) |
| Subject daycare attendance # | 730 (59.5%) | 714 (59.8%) |
| Number of house hold residents (Median (95%CI)) | 3 (2–4) | 3 (2–4) |
| Siblings or subject daycare attendance | 959 (78.2%) | 918 (76.9%) |
*
No infants developed BPD ** either exclusive breastfeeding or mixed with formula feeding # predicted by parents at birth.