Table 1 Demographic characteristics
|  | Antibiotic-naïve group (n=46) | Antibiotic-exposed group (n=22) | p-values |
|---|---|---|---|
Birth weight in g, median (range) | 1478.0 (688–1940) | 1173.0 (648–1924) | 0.003 |
Gestational age in weeks, median (range) | 31.5 (28–35) | 28.5 (24–32) | <0.001 |
Female gender, n (%) | 25 (54.3) | 12 (54.5) | 0.988 |
Multiple gestations, n (%) | 35 (76.1) | 17 (77.3) | 0.914 |
Race, n (%) | |||
 White | 23 (50.0) | 11 (50.0) | 1 |
 Black or African American | 18 (39.1) | 10 (45.5) | 0.62 |
 Asian | 2 (4.3) | 0 (0.0) | 0.321 |
 Native Hawaiian or other Pacific Islander | 1 (2.2) | 0 (0.0) | 0.486 |
 Unknown or not reported | 2 (4.3) | 1 (4.5) | 0.97 |
Hispanic or Latino, n (%) | 2 (4.3) | 1 (4.5) | 0.97 |
Cesarean section, n (%) | 42 (91.3) | 20 (90.9) | 0.957 |
Diet, n (%) | |||
 Mostly breast milk | 39 (84.8) | 19 (86.4) | 0.863 |
 Any receipt of formula | 4 (8.7) | 1 (4.5) | 0.54 |
 Any receipt of breast milk | 44 (95.7) | 22 (100.0) | 0.321 |
Perinatal maternal antibiotic exposure, n (%) | 39 (84.8) | 20 (90.9) | 0.486 |
Specimen collection time in days | |||
 Week 1 | 7 (5–9) | 6.5 (5–9) | 0.907 |
 Week 3 | 16 (15–21) | 17 (15–24) | 0.562 |