Biparietal Diameter (BPD)

Chervenak FA, Isaacson GC and Campbell S (eds).

Ultrasound in Obstetrics and Gynecology, 1992;

Table A1-2:pg 1778. Boston: Little Brown and Company

GA (wks)	-SD	Mean	+SD
12	18.5	20.6	22.5
13	21.5	23.8	26.1
14	26.4	28.8	31.2
15	27.8	30.4	33
16	31.6	33.9	36.2
17	37.8	38.4	41
18	38.4	41.1	43.8
19	42.1	43.9	45.7
20	44.1	47	48.9
21	47.3	50.1	52.9
22	49.9	53.1	56.3
23	53.6	57.3	61
24	56.1	59.5	62.9
25	59.6	62.1	64.6
26	62.7	65.9	69.1
27	66.4	70.1	73.8
28	70	72.8	75.6
29	71.6	76.4	79.6
30	74.2	76.8	79.4
31	76.2	79.8	83.5
32	79.1	82	84.9
33	78.8	83	87.2
34	82.1	85.5	88.4
35	84	87.3	90.6
36	84.8	89	93.2
37	86.5	90.8	95.1
38	88.4	92.4	96.4
39	89	94	99
40	91.2	94.8	98.4
41	93.7	95.8	97.9
42	94.2	97.5	100.8