Table 1. Characteristics of Actively Treated Infants in Each Cohorta.
| Characteristic | NRN | VON | ||
|---|---|---|---|---|
| 1998-2003 (n = 3702) | 2006-2012 (n = 4176) | 2006-2012 (n = 45 179) | 2013-2016 (n = 25 969) | |
| Prenatal care | 93 | 95 | 95 | 96 |
| Cesarean delivery | 48 | 58 | 64 | 65 |
| Antenatal corticosteroids | 80 | 85 | 79 | 86 |
| Race/ethnicity | ||||
| Blackb | 45 | 38 | 36 | 36 |
| Whiteb | 36 | 39 | 40 | 38 |
| Hispanicb | 17 | 15 | 19 | 20 |
| Singleton | 76 | 74 | 76 | 76 |
| Female | 47 | 48 | 47 | 48 |
| Gestational age, mean (SD), wk | 24.2 (0.8) | 24.2 (0.8) | 24.1 (0.8) | 24.1 (0.8) |
| Gestational age, wk | ||||
| 22 | 3 | 2 | 3 | 3 |
| 23 | 18 | 18 | 20 | 21 |
| 24 | 38 | 37 | 36 | 36 |
| 25 | 42 | 42 | 41 | 40 |
| Birth weight, mean (SD), g | 670 (118) | 676 (125) | 671 (125) | 671 (128) |
| Apgar score ≤3 | ||||
| 1 min | 50 | 57 | 50 | 52 |
| 5 min | 15 | 22 | 17 | 19 |
| Length of stay, median (5th-95th percentile), dc | 88 (0-177) | 96 (1-197) | 95 (1-188) | 102 (2-204) |
| Neonatal level of care at hospital of birthd | ||||
| Level III or IV NICU | 100 | 100 | 81 | 80 |
| Level II NICU | 0 | 0 | 17 | 18 |
| Level I NICU | 0 | 0 | 2 | 2 |
Abbreviations: NICU, neonatal intensive care unit; NRN, Neonatal Research Network; VON, Vermont Oxford Network.
Data are presented as percentage of infants unless otherwise indicated.
Maternal race/ethnicity determined by self-report as obtained by interview or, if unavailable, birth certificate or medical records.
In the 2006 to 2012 NRN cohort, 31 infants (0.7%) were still hospitalized at 1 year. In the 2006-2012 VON cohort, 241 infants (0.5%) were still hospitalized at 1 year. In the 2013 to 2016 VON cohort, 169 infants (0.6%) were still hospitalized at 1 year. Data were unavailable for the 1998-2003 NRN cohort.
The NICU designations include level I (restrictions on assisted ventilatory support), level II (no ventilatory support restrictions and no neonatal surgery), level III (no ventilatory support restrictions and perform neonatal surgery except cardiac surgery that requires bypass), and level IV (no ventilatory support restrictions and perform neonatal surgery, including cardiac surgery that required bypass). Because NICU designations can change over time and are assessed infrequently in the data sets, the proportions reported in the Table represent the designations most recently available at the end of each study period.