B超数据参考
| 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 | 6.9士1.65 | 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 | 2.1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1.89 | 2.71士0.46 |
| 19周 | 4.52士0.53 | 13.59士2.3 | 3.03士0.5 |
| 20周 | 4.88士0.58 | 14.8士1.89 | 3.35士0.47 |
| 21周 | 5.22士0.42 | 15.62士1.84 | 3.64士0.4 |
| 22周 | 5.45士0.57 | 16.7士2.23 | 3.82士0.47 |
| 23周 | 5.8士0.44 | 17.9士1.85 | 4.21士0.41 |
| 24周 | 6.05士0.5 | 18.74士2.23 | 4.36士0.51 |
| 25周 | 6.39士0.7 | 19.64士2.2 | 4.65士0.42 |
| 26周 | 6.68士0.61 | 21.62士2.3 | 4.87士0.41 |
| 27周 | 6.98士0.57 | 21.81士2.12 | 5.1士0.41 |
| 28周 | 7.24士0.65 | 22.86士2.41 | 5.35士0.55 |
| 29周 | 7.5士0.65 | 23.71士1.5 | 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0.6 | 25.78士2.32 | 6.03士0.38 |
| 32周 | 8.17士0.65 | 26.2士2.33 | 6.43士0.49 |
| 33周 | 8.5士0.47 | 27.78士2.3 | 6.42士0.46 |
| 34周 | 8.61士0.63 | 27.99士2.55 | 6.62士0.43 |
| 35周 | 8.7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 | 9.0士0.63 | 30.14士2.17 | 7.1士0.52 |
| 38周 | 9.08士0.59 | 30.63士2.83 | 7.2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0.5 | 31.49士2.79 | 7.4士0.53 |