Table 4. Comparison of neonatal survival rate according to gestational age for very-low-birth-weight infants in 6 networks form Korea, USA, Canada, Australian-New Zealand, and Europe countries.

GA	KNN	NRNJ	NICHD	CNN	AZN	GA	KNN	EuroNeonNet
	2013-2014. 6.	2012	2008-2011	2013	2012		2013-2014. 6.	2012
22	11.4	55.3†	5.2	25.0		≤ 23	33.8	20.8
23	41.1	73.8†	30.9	51.3	50.0
24	59.6	84.2†	61	67.5	70.3*	24-25	66.0	63.2
25	70.4	93.3†	75.7	78.9*	79.9*
26	79.0	94.6*	83.2	85.4	92.3†	26-27	83.0	86.2
27	86.2	95.6†	89	92.4*	92.9*
28	89.5	97.0†	93.5	94.2*	94.7*	28-29	92.0	94.4*
29	94.6	96.8		96.5	95.8
30	93.4	97.4†		98.2†	98.7†	30-31	95.3	96.9
31	97.4	98.0		98.8	98.0
≥ 32	97.8	95.8		98.7	97.6	≥ 32	97.8	98.1
22-28 weeks	74.7	90.6†	74.4	83.9†	87.3†
Total	84.8	93.8†		92.9†	95.2†		84.8	90.4†

^*P<0.05 comparison to the KNN reference birth weight specific survival rates; ^†P<0.001 comparison to the KNN reference birth weight specific survival rates. GA, gestational age, KNN; Korean Neonatal Network, NRNJ; Neonatal Research Network of Japan (reference 20), NICHD; National Institute of Child Health and Human Development Neonatal Research Network (U.S. (reference 1), CNN; Canadian Neonatal Network (reference 21), AZN; Australia-New Zealand Neonatal Network (reference 22), EuroNeoNet; European Neonatal Network (reference 23).