General characteristics of the study group.
| Characteristics | Total group (n=215254) | Preterm group (n=15833) | Term group (n=199421) | P-value |
| Gestational age (weeks)* | 38±2 | 34±2 | 39±1 | <0.001 |
| Birth weight (g)* | 3262±500 | 2419±583 | 3329±4263 | <0.001 |
| Male † | 114084 (53.0) | 9212 (58.0) | 105094 (52.7) | 0.001 |
| Maternal age (years) † | 27.4±4.9 | 27.7±5.6 | 27.4±4.8 | <0.001 |
| Parity † | #x00A0; | #x00A0; | #x00A0; | <0.001 |
| 1 | 149951 (69.7) | 9949 (62.8) | 140002 (70.2) | #x00A0; |
| ≥2 | 65303 (30.3) | 5884 (37.2) | 59419 (29.8) | #x00A0; |
| Apgar score at 5 min of <7 | 600 (2.8) | 335 (2.1) | 265 (1.3) | <0.001 |