Baseline information of infants in the present study
| Variable | Perforation group (n=113) | Non-perforation group (n=485) | Statistics | P value |
| Male, n (%) | 76 (69.9) | 255 (52.6) | χ2=211.168 | 0.001 |
| Gestational age (wk), median (IQR) | 36.57 (33.43–38.86) | 37.86 (35.14–39.21) | Z=2.656 | 0.008 |
| Birth weight (g), median (IQR) | 2500 (2020–3200) | 2800 (2250–3250) | Z=1.800 | 0.072 |
| Age at admission (d), median (IQR) | 4 (2–8) | 3.25 (1-10) | Z=0.705 | 0.481 |
| Age at examination (d), median (IQR) | 6 (3.5–10) | 9 (4–15) | Z=2.662 | 0.008 |
| Premature rupture of membranes, n (%) | 22 (19.55) | 105 (21.6) | χ2=20.260 | 0.610 |
| Small for gestational age, n (%) | 19 (16.8) | 73 (15.1) | χ2=20.219 | 0.640 |
| Amniotic fluid contamination, n (%) | 9 (8) | 59 (12.2) | χ2=21.604 | 0.205 |
| Vaginal delivery, n (%) | 36 (31.9) | 166 (34.2) | χ2=20.230 | 0.632 |
| Twins, n (%) | 22 (19.5) | 72 (14.8) | χ2=21.479 | 0.224 |
| Feeding mode, n (%) | χ2=26.246 | 0.100 | ||
| Breast milk | 16 (14.2) | 88 (18.1) | ||
| Formula milk | 53 (46.9) | 205 (42.3) | ||
| Mixed feeding | 24 (21.2) | 138 (28.5) | ||
| No feeding | 20 (17.7) | 54 (11.1) |
IQR, interquartile range.