Table 2b. Rates of IVH, severe IVH, survival, and IVH-free survival by gestational age.

Gestational age category	n		IVH			Grade III/IV IVH or death with no ultrasound performed			Survival			IVH-free survival
	Before	After	Before	After	p-value	Before	After	p-value	Before	After	p-value	Before	After	p-value
<24 wks	26	13	61.5%	30.8%	0.141	26.9%	15.4%	0.687	76.9%	92.3%	0.461	30.8%	69.2%	0.052
24 to 25 wks	71	32	31.0%	25.0%	0.701	18.3%	6.3%	0.192	90.1%	87.5%	0.955	62.0%	65.6%	0.893
26 to 27 wks	48	48	20.8%	6.3%	0.074	8.3%	4.2%	0.673	95.8%	91.7%	0.673	77.1%	87.5%	0.285
28 to 29 wks	56	45	8.9%	8.9%	0.731	0.0%	0.0%		98.2%	100.0%	0.912	89.3%	91.1%	0.976
≥30 wks	62	53	8.1%	1.9%	0.287	0.0%	1.9%	0.937	100.0%	94.3%	0.190	91.9%	94.3%	0.891
<28 wks	145	93	33.1%	16.1%	0.006	16.6%	6.5%	0.037	89.7%	90.3%	0.944	61.4%	77.4%	0.015
Total	263	191	22.1%	10.5%	0.002	9.1%	3.7%	0.037	93.9%	93.7%	0.912	74.5%	85.3%	0.007

IVH: intraventricular hemorrhage; p-value: significance level