Table 4.

The normal reference ranges of fetal left ventricular IRT based on the cross-sectional data with the manual and automatic measurements

Weeks of gestation	No	Mean	SD	Percentile
				5	10	25	50	75	90	95
20–24 weeks
Manual	1710	40	6	29	33	37	41	44	47	49
Auto	1528	42	5	33	36	39	42	45	48	50
28–32 weeks
Manual	1486	41	6	30	34	38	42	46	49	51
Auto	1475	42	6	34	36	39	42	46	50	52
34–38 weeks
Manual	1178	42	7	29	33	38	42	46	50	52
Auto	1057	43	6	34	36	39	42	47	51	53

IRT, isovolumetric relaxation time.