孕期正常参数值 
孕周 双顶径(平均值)cm 腹围(平均值)cm 股骨长(平均值)cm 
16周 3.62士0.58 10.32士1.92 2.10士0.51 
18周 4.25士0.53 12.41士l.89 2.71士0.46 
20周 4.88士0.58 14.80士l.89 3.35士O.47 
22周 5.45士0.57 16.70士2.23 3.82士0.47 
24周 6.05士0.50 18.74士2.23 4.36士0.51 
26周 6.68士0.61 21.62士2.30 4.87士O.41 
28周 7.24士O.65 22.86士2.41 5.35士0.55 
30周 7.83士0.62 24.88士2.03 5.77士0.47 
32周 8.17士0.65 26.20士2.33 6.43士0.49 
34周 8.61士0.63 27.99士2.55 6.62士0.43 
36周 8.81士0.57 29.44士2.83 6.95士0.47 
38周 9.08士0.59 30.63士2.83 7.20士0.43 
39周 9.21士0.59 31.34士3.12 7.34士0.53 
40周 9.28士0.50 31.49士2.79 7.40士0.53