Subanalysis of infants with paired Hct at 0–4 and 4–24 hours after birth showing that Hct increases over 24 hours in infants <33 weeks’ gestation (n=174)
| GA, weeks | Infants (n) | Hct (n) | Hct at 0–4 hours, M (SD) | Hct at 4–24 hours, M (SD) | Difference, M (SD) | Adjusted* | ||
| β | 95% CI | P value | ||||||
| 23–34 | 174 | 348 | 51.5 (8.5) | 53.6 (8.6) | 2.1 (5.7) | 0.1 | 0.1 to 0.2 | <0.001 |
| Strata | ||||||||
| 23–29 | 50 | 100 | 46.4 (6.9) | 49.2 (8.1) | 2.8 (6.1) | 0.2 | 0.1 to 0.3 | 0.003 |
| 30–31 | 28 | 56 | 50.9 (8.0) | 55.1 (9.0) | 4.2 (4.9) | 0.2 | 0.1 to 0.4 | <0.001 |
| 32 | 30 | 60 | 50.3 (6.6) | 52.7 (7.5) | 2.4 (4.5) | 0.1 | 0.0 to 0.2 | 0.026 |
| 33 | 33 | 66 | 55.2 (8.9) | 55.3 (8.7) | 0.1 (6.6) | 0 | −0.2 to 0.2 | 0.980 |
| 34 | 33 | 66 | 57.3 (7.8) | 58.1 (7.2) | 0.9 (5.2) | 0 | −0.1 to 0.2 | 0.644 |
*Three-tiered, multilevel, mixed-effects linear regression model adjusted for gestational age and clustered by mother and infant.
Hct, haematocrit.