Table 3:

Median, 5th, and 95th percentiles for perimeter measurements

Gestational Age (wk)	Imaging Modality
	US 2D			US 3D			MRI
	%5	Median	%95	%5	Median	%95	%5	Median	%95
21	36.20	40.94	44.80	37.20	41.70	54.60
22	37.04	46.80	48.64	40.60	47.30	49.40
23	41.20	45.07	49.39	41.50	46.90	55.20
24	48.10	49.89	51.80	45.00	49.20	56.70
25	46.74	52.41	62.86	48.80	53.30	63.30
26	50.00	57.87	65.98	50.80	58.30	68.60
27	48.97	59.08	67.10	51.40	64.00	69.30	50.05	50.67	57.75
28	53.26	60.42	69.40	57.60	66.20	82.60	48.22	53.30	58.16
29	58.58	65.42	69.37	58.80	66.40	77.20	50.58	56.85	61.09
30	60.08	64.98	70.36	57.80	70.20	82.80	55.07	61.10	72.13
31	61.18	65.67	71.97	64.10	71.10	82.40	59.38	66.21	71.93
32	62.13	67.31	77.88	65.30	74.60	96.10	61.20	68.11	73.79
33	68.13	71.38	76.83	73.70	77.95	82.50	64.98	70.90	78.33
34	67.05	73.97	80.43	66.50	80.10	92.80	67.21	71.06	83.00
35	70.20	75.19	79.16	68.50	79.70	100.20	69.44	75.93	86.11

Note:—%5 indicates 5th percentile; %95, 95th percentile.