Hadlock Ultrasound Measurements Based on Gestational Age
Ultrasound
Obie Editorial Team
How big should your baby be now?
This chart outlines expected ultrasound measurements (in mm) based on gestational age.
BPD: biparietal diameter (the diameter between the 2 sides of the head
HC: head circumference
AC: abdominal circumference
FL: femur length
| Weeks | BPD (mm) | HC (mm) | AC (mm) | FL (mm) |
| 16 | 32.3 | 124.4 | 99.1 | 20.5 |
| 16.5 | 34.2 | 131.2 | 105.5 | 22.1 |
| 17 | 36.0 | 137.9 | 111.9 | 23.7 |
| 17.5 | 37.7 | 144.5 | 118.2 | 25.2 |
| 18 | 39.5 | 151.1 | 124.5 | 26.7 |
| 18.5 | 41.3 | 157.7 | 130.7 | 28.3 |
| 19 | 43.0 | 164.1 | 136.9 | 29.8 |
| 19.5 | 44.7 | 170.5 | 143.0 | 31.2 |
| 20 | 46.4 | 176.8 | 149.1 | 32.7 |
| 20.5 | 48.1 | 183.0 | 155.1 | 34.1 |
| 21 | 49.7 | 189.2 | 161.1 | 35.6 |
| 21.5 | 51.4 | 195.3 | 167.0 | 37.0 |
| 22 | 53.0 | 201.3 | 172.9 | 38.4 |
| 22.5 | 54.6 | 207.2 | 178.7 | 39.8 |
| 23 | 56.2 | 213.0 | 184.5 | 41.1 |
| 23.5 | 57.8 | 218.7 | 190.2 | 42.5 |
| 24 | 59.3 | 224.4 | 195.9 | 43.8 |
| 24.5 | 60.8 | 229.9 | 201.5 | 45.1 |
| 25 | 62.3 | 235.4 | 207.1 | 46.4 |
| 25.5 | 63.8 | 240.8 | 212.7 | 47.7 |
| 26 | 65.3 | 246.0 | 218.1 | 48.9 |
| 26.5 | 66.7 | 251.2 | 223.6 | 50.2 |
| 27 | 68.1 | 256.2 | 228.9 | 51.4 |
| 27.5 | 69.5 | 261.2 | 234.3 | 52.6 |
| 28 | 70.8 | 266.1 | 239.6 | 53.8 |
| 28.5 | 72.2 | 270.8 | 244.8 | 55.0 |
| 29 | 73.5 | 275.5 | 250.0 | 56.1 |
| 29.5 | 74.7 | 280.0 | 255.1 | 57.3 |
| 30 | 76.0 | 284.4 | 260.2 | 58.4 |
| 30.5 | 77.2 | 288.7 | 265.2 | 59.5 |
| 31 | 78.4 | 292.9 | 270.2 | 60.6 |
| 31.5 | 79.6 | 297.0 | 275.1 | 61.7 |
| 32 | 80.7 | 300.9 | 280.0 | 62.7 |
| 32.5 | 81.9 | 304.7 | 284.8 | 63.8 |
| 33 | 82.9 | 308.4 | 289.6 | 64.8 |
| 33.5 | 84.0 | 312.0 | 294.3 | 65.8 |
| 34 | 85.0 | 315.5 | 299.0 | 66.8 |
| 34.5 | 86.0 | 318.8 | 303.7 | 67.7 |
| 35 | 87.0 | 322.0 | 308.2 | 68.7 |
| 35.5 | 87.9 | 325.0 | 312.8 | 69.6 |
| 36 | 88.8 | 327.9 | 317.3 | 70.6 |
| 36.5 | 89.7 | 330.7 | 321.7 | 71.5 |
| 37 | 90.5 | 333.3 | 326.1 | 72.3 |
| 37.5 | 91.3 | 335.8 | 330.4 | 73.2 |
| 38 | 92.1 | 338.2 | 334.7 | 74.1 |
| 38.5 | 92.8 | 340.4 | 338.9 | 74.9 |
| 39 | 93.5 | 342.5 | 343.1 | 75.7 |
| 39.5 | 94.2 | 344.4 | 347.2 | 76.5 |
| 40 | 94.8 | 346.1 | 351.3 | 77.3 |
| 40.5 | 95.4 | 347.7 | 355.4 | 78.1 |
| 41 | 95.9 | 349.2 | 359.3 | 78.8 |
| 41.5 | 96.5 | 350.5 | 363.3 | 79.5 |
| 42 | 96.9 | 351.6 | 367.2 | 80.3 |
Hadlock Formulas: Haddlock Radiology 1984; 152: 497-501
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