Table 1.

The values that define the lowest and highest quartiles of each blood gas on each day in each gestational age group.

Blood gas quartile →	Lowest PO2 (mm Hg)			Highest PO2 (mm Hg)
Postnatal day →	1	2	3	1	2	3
Gestational age (wks) ↓
23-24	39	43	44	152	98	104
25-26	42	45	45	145	100	95
27	40	44	46	142	92	96
Blood gas quartile →	Lowest PCO2 (mm Hg)			Highest PCO2 (mm Hg)
Postnatal day →	1	2	3	1	2	3
Gestational age (wks) ↓
23-24	27	33	34	65	68	63
25-26	29	35.5	35	60	64	60
27	29	35	36	58	57	56