Table 1. Baseline perinatal data and type of milk feeding.
| Characteristics | Group 1 (n = 1288) | Group 2 (n = 673) | p-value |
|---|---|---|---|
| Perinatal | |||
| Gender (male) | 665 (52) | 360 (54) | 0.43 |
| Gestational age (week) | 29.4 (27.3–31.0) | 29.6 (27.1–31.0) | 0.96 |
| Extremely preterm <28 weeks | 421 (33) | 213 (32) | 0.64 |
| Birth weight (g) | 1163 (885–1425) | 1175 (915–1453) | 0.24 |
| SGA | 48 (4) | 27 (4) | 0.76 |
| ELBW | 468 (36) | 235 (35) | 0.53 |
| Singleton pregnancy | 968 (75) | 526 (78) | 0.14 |
| Inborn delivery | 1165 (91) | 607 (90) | 0.86 |
| Ceasarean section | 722 (56) | 427 (63) | <0.01 |
| Prenatal steroidsa | 1130 (88) | 601 (89) | 0.34 |
| Mother prenatal antibioticsb | 68 (5) | 22 (5) | 0.50 |
| Infant direct postnatal antibiotics | 1144 (89) | 601 (89) | 0.75 |
| Apgar score at 5 minc | 8 (7–9) | 8 (7–9) | 0.46 |
| Cord arterial pHd | 7.29 (7.23–7.33) | 7.30 (7.23–7.35) | 0.06 |
| Type of milk feeding | |||
| Only breast milk | 63 (4.9) | 151 (22) | <0.001 |
| Mixed (breast milk and formula) | 965 (75) | 385 (57) | <0.001 |
| Only formula | 239 (19) | 88 (13) | <0.01 |
| ENS study milk | 0 | 24 (4) | <0.001 |
| No milk | 21 (2) | 25 (4) | <0.01 |
Shown are numbers (%) for categorical variables and medians (interquartile range) for continuous variables for patients born before (group 1) and after (group 2) introduction of routine probiotic treatment, and p-values.
Footnotes indicating number of missings: a43 (35 and 8 per group respectively); b204 (15 and 189, without clear explanation for difference); c21 (9 and 12); dnot performed in 259 (142 and 117).
Abbreviations: CI, confidence interval; ELBW, extremely low birth weight; ENS: Early Nutrition Study milk (donor milk or formula); SGA, small for gestational age
Definitions: ELBW, defined as BW < 1000 g; SGA, defined as birth weight (BW) for GA < −2 SD.