Table 2.
Univariate Analysis.
| Variable | Necrotizing enterocolitis | ||
|---|---|---|---|
| No (n = 9649) | Yes (n = 704) | P value | |
| Gestational age < 28 weeks | 3412 (35.4) | 490 (69.6) | < 0.001* |
| Gestational age < 26 weeks | 1582 (16.4) | 292 (41.5) | < 0.001* |
| Birth weight < 1000 g | 3413 (35.4) | 487 (69.2) | < 0.001* |
| Birth weight < 750 g | 1360 (14.1) | 251 (35.7) | < 0.001* |
| Small-for-gestational-age | 2103 (21.9) | 121 (17.4) | 0.008* |
| Sex (male) | 4852 (50.3) | 386 (54.8) | 0.048* |
| Birth-Year, n (%) | 0.017* | ||
| 2013 | 1290 (13.4) | 102 (14.5) | |
| 2014 | 1988 (20.6) | 131 (18.6) | |
| 2015 | 2234 (23.2) | 146 (20.7) | |
| 2016 | 2173 (22.5) | 173 (24.6) | |
| 2017 | 1964 (20.4) | 152 (21.6) | |
| Birth-Season: Spring | 2339 (24.2) | 174 (24.7) | 0.365 |
| Birth-Season: Summer | 2422 (25.2) | 186 (26.4) | 0.569 |
| Birth-Season: Autumn | 2549 (26.4) | 189 (26.8) | 0.774 |
| Birth-Season: Winter | 2339 (24.2) | 155 (22.2) | 0.164 |
| Temperature average Year | 14.14 ± 0.62 | 14.15 ± 0.64 | 0.654 |
| Temperature minimum Year | 8.87 ± 0.84 | 8.90 ± 0.87 | 0.446 |
| Temperature maximum Year | 20.22 ± 0.50 | 20.21 ± 0.52 | 0.788 |
| PM10 Year | 47.09 ± 0.59 | 47.11 ± 0.57 | 0.301 |
| PM10 10-month before birth | 46.28 ± 9.13 | 46.66 ± 9.55 | 0.307 |
| PM10 09-month before birth | 46.52 ± 9.20 | 46.13 ± 8.94 | 0.265 |
| PM10 08-month before birth | 46.77 ± 9.32 | 46.90 ± 9.58 | 0.728 |
| PM10 07-month before birth | 47.07 ± 9.40 | 46.93 ± 9.35 | 0.702 |
| PM10 06-month before birth | 46.86 ± 9.24 | 46.94 ± 9.48 | 0.829 |
| PM10 05-month before birth | 46.66 ± 9.35 | 46.04 ± 8.94 | 0.077 |
| PM10 04-month before birth | 46.38 ± 9.40 | 46.05 ± 9.41 | 0.369 |
| PM10 03-month before birth | 46.12 ± 9.51 | 46.12 ± 9.61 | 1.000 |
| PM10 02-month before birth | 45.97 ± 9.42 | 46.47 ± 9.64 | 0.184 |
| PM10 01-month before birth | 45.98 ± 9.33 | 45.99 ± 8.96 | 0.977 |
| PM10 00-month before birth | 46.17 ± 9.32 | 46.54 ± 9.24 | 0.306 |
| Multiple pregnancy | 3412 (35.4) | 225 (32.0) | 0.188 |
| Multipara | 3614 (37.5) | 291 (41.3) | 0.050* |
| In vitro fertilization | 2245 (23.3) | 144 (20.5) | 0.192 |
| Gestational DM | 794 (8.2) | 32 (4.5) | 0.002* |
| Overt DM | 108 (1.1) | 6 (0.9) | 0.546 |
| Pregnancy-induced hypertension | 1859 (19.3) | 114(16.6) | 0.134 |
| Chronic hypertension | 205 (2.1) | 16 (2.3) | 0.886 |
| Chorioamnionitis | 2765 (28.7) | 224 (31.8) | 0.001* |
| PROM > 18 h | 2273 (23.6) | 182 (25.9) | < 0.001* |
| Antenatal steroid | 7507 (77.8) | 564 (80.1) | < 0.001* |
| Cesarean section | 7545 (78.2) | 507 (72) | 0.001* |
| Oligohydramnios | 1309 (13.6) | 90 (12.8) | < 0.001* |
| Polyhydramnios | 144 (1.5) | 9 (1.3) | 0.001* |
| Congenital infection | 115 (1.2) | 12(1.7) | 0.485 |
| 1-min Apgar score ≤ 3 | 2667 (27.6) | 308 (43.8) | < 0.001* |
| 5-min Apgar score < 7 | 3142 (32.6) | 346 (49.1) | < 0.001* |
| Neonatal resuscitation program | 8508 (88.2) | 661 (93.9) | < 0.001* |
| Neonatal resuscitation program, intensive | 5888 (61.0) | 578(82.1) | < 0.001* |
| Blood gas pH < 7.0 | 210 (2.2) | 24 (3.4) | < 0.001* |
| Blood gas base excess < -15 | 205 (2.1) | 30 (4.3) | < 0.001* |
| Pulmonary hemorrhage | 532 (5.5) | 104 (14.8) | < 0.001* |
| Respiratory distress syndrome | 7414 (76.8) | 644 (91.5) | < 0.001* |
| Surfactant use ≥ 2 | 1860 (19.3) | 221 (31.4) | < 0.001* |
| Patent ductus arteriosus treatment | 3348 (34.7) | 357 (50.7) | < 0.001* |
| Patent ductus arteriosus ligation | 934 (9.7) | 165 (23.4) | < 0.001* |
| Air leak syndrome | 485 (5.0) | 84 (11.9) | < 0.001* |
| Sepsis | 1854 (19.2) | 323 (45.9) | < 0.001* |
Values are presented as number (%) or mean ± standard deviation.
Abbreviations: DM, Diabetes mellitus; PROM, Pre-labor rupture of membrane; PM10, particulate matter concentration.
*P < 0.05 Chi-Square Test for the Equality of Proportions “Yes” or T Test for the Equality of Means.