孕周 双顶径(平均值)cm 腹围(平均值)cm 股骨长(平均值)cm 13周 2.52士0.25 6.90士l.65 1.17士0.31 14周 2.83士0.57 7.77士1.82 1.38士0.48 15周 3.23士0.51 9.13士1.56 1.74士0.58 16周 3.62士0.58 10.32士1.92 2.10士0.51 17周 3.97士0.44 11.49士1.62 2.52士0.44 18周 4.25士0.53 12.41士l.89 2.71士0.46 19周 4.52士0.53 13.59士2.30 3.03士0.50 20周 4.88士0.58 14.80士l.89 3.35士0.47 21周 5.22士0.42 15.62士1.84 3.64士0.40 22周 5.45士0.57 16.70士2.23 3.82士0.47 23周 5.80士0.44 17.90士1.85 4.21士0.41 24周 6.05士0.50 18.74士2.23 4.36士0.51 25周 6.39士0.70 19.64士2.20 4.65士0.42 26周 6.68士0.61 21.62士2.30 4.87士0.41 27周 6.98士0.57 21.81士2.12 5.10士0.41 28周 7.24士0.65 22.86士2.41 5.35士0.55 29周 7.50士0.65 23.71士1.50 5.61士0.44 30周 7.83士0.62 24.88士2.03 5.77士0.47 31周 8.06士0.60 25.78士2.32 6.03士0.38 32周 8.17士0.65 26.20士2.33 6.43士0.49 33周 8.50士0.47 27.78士2.30 6.52士0.46 34周 8.61士0.63 27.99士2.55 6.62士0.43 35周 8.70士0.55 28.74士2.88 6.71士0.45 36周 8.81士0.57 29.44士2.83 6.95士0.47 37周 9.00士0.63 30.14士2.17 7.10士0.52 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