Table 1.
Age, number and sex of the fetuses studied
| Gestational age (weeks) |
Crown–rump length (mm) | Number of fetuses | Sex | ||||
|---|---|---|---|---|---|---|---|
| Mean | SD | Min. | Max. | ♂ | ♀ | ||
| 17 | 116.00 | 1.41 | 115.00 | 117.00 | 2 | 1 | 1 |
| 18 | 130.00 | 0.00 | 130.00 | 130.00 | 2 | 1 | 1 |
| 19 | 150.00 | 3.03 | 146.00 | 154.00 | 6 | 3 | 3 |
| 20 | 159.50 | 0.71 | 159.00 | 160.00 | 2 | 1 | 1 |
| 21 | 174.75 | 2.87 | 171.00 | 178.00 | 4 | 3 | 1 |
| 22 | 184.67 | 1.53 | 183.00 | 186.00 | 3 | 1 | 2 |
| 23 | 197.75 | 2.99 | 195.00 | 202.00 | 4 | 3 | 1 |
| 24 | 208.57 | 3.74 | 204.00 | 213.00 | 7 | 4 | 3 |
| 25 | 214.50 | 0.71 | 214.00 | 215.00 | 2 | 1 | 1 |
| 26 | 226.00 | 1.41 | 225.00 | 227.00 | 2 | 1 | 1 |
| 27 | 237.75 | 2.75 | 235.00 | 241.00 | 4 | 3 | 1 |
| 28 | 246.67 | 4.93 | 241.00 | 250.00 | 3 | 1 | 2 |
| 29 | 254.00 | 1.41 | 253.00 | 255.00 | 2 | 1 | 1 |
| 30 | 263.25 | 1.26 | 262.00 | 265.00 | 4 | 1 | 3 |
| Total | 47 | 25 | 22 | ||||