Fetal Staging Guide

Post Conception Weeks (PCW)	Foot Length (mm)	Knee to Heel Length (mm)	Gestational Age in Weeks
Late 8	5 and above, and less than 6	8	10
9	6 or above and less than 8	11	11
10	8 or above and less than 10	13	12
11	10 or above and less than 13	17	13
12	13 or above and less than 17	24	14
13	17 or above and less than 20	31	15
14	20 or above and less than 23	36	16
15	23 or above and less than 25	40	17
16	25 or above and less than 27	43	18
17	27 or above and less than 31	51	19
18	31 or above and less than 33	56	20
19	33 or above and less than 36	60	21
20	36 or above and less than 40	66	22

W.M. Hern. Correlation of Fetal Age and Measurements between 10 and 26 weeks of Gestation, Obstetrics and Gynecology. Vol 63, No1, 26-32, January 1984.