Baseline characteristics of study cohort overall and by ABT group
| Variables | n | Study cohort (N=1762) n (%)** | ABT group | P value | |||
| No ABT (n=548) n (%)** | ABT start, day 1 or 2 (n=973) n (%)** | ABT start, days 3–6 (n=147) n (%)** | ABT start, day ≥7 (n=94) n (%) | ||||
| Gestational age (weeks): mean (±SD) | 1762 | 29 (±2.8) | 31.1 (±2.1) | 27.7 (±2.5) | 29.0 (±2.4) | 30.0 (±2.3) | <0.001ANOVA |
| Birth weight (g): median (IQR) | 1762 | 1055.0 (760.0–1310.0) | 1263.5 (1086.3–1400.0) | 920.0 (682.5–120.0) | 910.0 (710.0–1230.0) | 1052.5 (843.8–1308.8) | <0.001KW |
| Sex (male), n (%) | 1762 | 856 (48.6) | 242 (44.2) | 495 (50.9) | 79 (53.7) | 40 (42.6) | 0.03Chi |
| Multiples, n (%) | 1762 | 738 (41.9) | 257 (46.8) | 389 (40.0) | 49 (33.3) | 43 (45.7) | 0.01Chi |
| SGA, n (%) | 1762 | 553 (31.4) | 231 (42.3) | 217 (22.3) | 61 (41.5) | 44 (46.8) | <0.001Chi |
| Antenatal steroids, n (%) | 1745 | 1606 (92.0) | 483 (89.3) | 905 (93.8) | 138 (93.9) | 80 (87.0) | .004Chi |
| Mode of delivery, n (%) | 1762 | <0.001Chi | |||||
| Spontaneous | 112 (6.4) | 19 (3.4) | 88 (9.0) | 3 (2.0) | 2 (2.1) | ||
| Elective C/S | 1109 (62.9) | 389 (70.8) | 524 (53.9) | 120 (81.6) | 76 (80.9) | ||
| Emergency C/S | 541 (30.7) | 140 (25.8) | 361 (37.1) | 24 (16.3) | 16 (17.0) | ||
| Apgar score | |||||||
| 5 min, n median (IQR) (%) | 1761 | 8.0 (7.0–9.0) | 9.0 (8.0–9.0) | 8.0 (7.0–9.0) | 8.0 (8.0–9.0) | 8.0 (7.0–9.0) | <0.001KW |
| 10 min, n median (IQR) (%) | 1761 | 9.0 (8.0–9.0) | 9.0 (9.0–10.0) | 9.0 (8.0–9.0) | 9.0 (8.0–9.0) | 9.0 (8.0–9.0) | <0.001KW |
| Arterial cord blood pH, median (IQR) | 1657 | 7.31 (7.26–7.35) | 7.30 (7.26–7.34) | 7.32 (7.27–7.36) | 7.30 (7.26–7.34) | 7.30 (7.26–7.35) | <0.001KW |
| Base excess (mmol/L), median (IQR) | 1488 | −2.0 (−3.9 to −0.5) | −2.0 (−3.7 to −0.6) | −2.6 (−4.0 to −0.5) | −2.0 (−3.9 to 0.2) | −1.6 (−4.0 to −0.4) | 0.66KW |
| IAI, n (%) | 1762 | 356 (20.2) | 53 (9.6) | 285 (29.3) | 9 (6.1) | 9 (9.6) | <0.001Chi |
| pPROM, n (%) | 1641 | 434 (26.4) | 77 (14.9) | 331 (37.0) | 11 (8.0) | 15 (16.5) | <0.001Chi |
| Central line, n (%) | 1762 | 521 (29.6) | 24 (4.4) | 414 (42.5) | 54 (36.7) | 29 (30.9) | <0.001Chi |
| Arterial line, n (%) | 1762 | 78 (4.4) | 5 (0.9) | 65 (6.7) | 8 (5.4) | 0 (0.0) | <0.001Fis |
| Intratracheal ventilation, n (%) | 1762 | 821 (46.6) | 56 (10.2) | 650 (66.8) | 83 (56.5) | 32 (34.0) | <0.001Chi |
*Unless otherwise stated.
ABT, antibiotic therapy; ANOVA, analysis of variance; Chi, χ2 test; C/S, caesarean section; Fis, Fisher's exact test; IAI, intra-amniotic infection; KW, Kruskal-Wallis test; pPROM, preterm premature rupture of membranes; SGA, small for gestational age.