Table 4. International comparison of demographics and morbidities of VLBWIs (24–31 weeks' gestation).
| Variables | KNNa (n = 6,620) | ANZNNb (n = 9,643) | CNNb (n = 8,666) | INNb (n = 4,481) | NRNJb (n = 12,608) | SEN1500b (n = 8,063) | SwissNeoNetb (n = 2,034) | UKNCc (n = 10,325) |
|---|---|---|---|---|---|---|---|---|
| Multiple birth | 35 (33–36) | 31 (30–32) | 31 (30–32) | 42 (41–44) | 24 (23–25) | 33 (32–34) | 34 (32–36) | 28 (27–29) |
| Sex, male | 51 (50–52) | 51 (50–52) | 52 (51–53) | 52 (51–54) | 52 (51–53) | 52 (51–53) | 52 (49–54) | 51 (50–52) |
| Antenatal steroid | 81 (80–82) | 90 (89–90) | 84 (84–85) | 75 (74–77) | 49 (49–50) | 84 (84–85) | 89 (88–90) | 82 (81–83) |
| Cesarean section | 77 (76–78) | 64 (63–65) | 62 (61–63) | 73 (72–75) | 77 (76–77) | 67 (66–68) | 84 (83–86) | 47 (46–48) |
| BPD | 33 (32–34) | 24 (23–25) | 25 (24–26) | 14 (13–15) | 19 (18–20) | 15 (14–16) | 13 (11–15) | 32 (31–33) |
| IVH (≥ grade III) | 10 (9–11) | 6 (6–7) | 10 (9–11) | 12 (11–13) | 4 (4–5) | 10 (9–11) | 8 (7–9) | 6 (6–6) |
| PVL | 7 (6–9) | 3 (2–3) | 6 (5–7) | 5 (4–6) | 4 (4–4) | 6 (6–7) | 2 (2–3) | 2 (2–2) |
| ROP Tx. | 8 (8–9) | 3 (3–3) | 4 (4–4) | 3 (3–4) | 16 (16–17) | 4 (4–5) | 2 (1–3) | 2 (2–3) |
Data are presented as survival rate (range of probability: 95% confidence interval). There is a significant difference among groups if the probability ranges do not overlap with each other.
VLBWIs = very low birth weight infants, BPD = bronchopulmonary dysplasia, moderate to severe, IVH (≥ grade III) = grade III or more intraventricular hemorrhage, PVL = periventricular leukomalacia, cystic, ROP Tx. = therapy for retinopathy of prematurity before discharge from the neonatal intensive care unit, KNN = Korean Neonatal Network, ANZNN = Australia and New Zealand Neonatal Network, CNN = Canadian Neonatal Network, INN = the Israel Neonatal Network, NRNJ = Neonatal Research Network of Japan, SEN1500 = Spanish Neonatal Network, UKNC = United Kingdom Neonatal Collaborative.
a2013–2016; b2007–2010; c2008–2010.