A fetal development reference tool based on authoritative consensus, providing standard ranges for key parameters like BPD and head circumference by gestational week.
Data compiled from the Expert Consensus on Ultrasound Reference Values for Fetal Biometry (unit: mm).
| Gestational Week | Biparietal Diameter (BPD) | Head Circumference (HC) | Abdominal Circumference (AC) | Femur Length (FL) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | Standard | High | Low | Standard | High | Low | Standard | High | Low | Standard | High | |
| 10 | 10 | 11.8 | 14.1 | 39.9 | 45.9 | 52.7 | 30.9 | 36 | 42 | 1.6 | 2.2 | 2.9 |
| 11 | 12.9 | 15.2 | 17.9 | 50.6 | 57.8 | 66 | 39.2 | 45.4 | 52.5 | 2.9 | 3.8 | 5 |
| 12 | 16.1 | 18.9 | 22.1 | 62.2 | 70.6 | 80.2 | 48.4 | 55.7 | 64.1 | 4.7 | 6.1 | 7.8 |
| 13 | 19.4 | 22.6 | 26.4 | 74.3 | 83.9 | 94.7 | 58.3 | 66.8 | 76.5 | 7 | 8.9 | 11.3 |
| 14 | 22.8 | 26.4 | 30.6 | 86.6 | 97.3 | 109.3 | 68.8 | 78.4 | 89.4 | 9.8 | 12.2 | 15.3 |
| 15 | 26.1 | 30.1 | 34.7 | 98.9 | 110.5 | 123.5 | 79.7 | 90.4 | 102.5 | 12.7 | 15.7 | 19.3 |
| 16 | 29.3 | 33.6 | 38.5 | 110.9 | 123.3 | 137.1 | 90.8 | 102.5 | 115.6 | 15.7 | 19.1 | 23.3 |
| 17 | 32.4 | 36.9 | 42.1 | 122.6 | 135.6 | 150 | 101.8 | 114.5 | 128.6 | 18.7 | 22.4 | 26.9 |
| 18 | 35.3 | 40 | 45.4 | 133.9 | 147.5 | 162.3 | 112.9 | 126.3 | 141.4 | 21.4 | 25.4 | 30.1 |
| 19 | 38.1 | 43.1 | 48.6 | 145.1 | 159 | 174.3 | 123.8 | 138 | 153.9 | 24.1 | 28.2 | 33.1 |
| 20 | 41 | 46.1 | 51.8 | 156.4 | 170.7 | 186.2 | 134.6 | 149.6 | 166.3 | 26.7 | 31 | 36 |
| 21 | 44 | 49.2 | 55.1 | 167.8 | 182.4 | 198.1 | 145.3 | 161.1 | 178.6 | 29.4 | 33.8 | 38.8 |
| 22 | 47 | 52.3 | 58.4 | 179.3 | 194 | 210 | 155.9 | 172.4 | 190.6 | 32.1 | 36.5 | 41.5 |
| 23 | 49.9 | 55.5 | 61.6 | 190.7 | 205.7 | 221.8 | 166.2 | 183.4 | 202.5 | 34.7 | 39.1 | 44.2 |
| 24 | 52.9 | 58.6 | 64.9 | 201.9 | 217.1 | 233.5 | 176.3 | 194.3 | 214.1 | 37.2 | 41.7 | 46.8 |
| 25 | 55.9 | 61.7 | 68.1 | 212.9 | 228.3 | 244.9 | 186.1 | 204.9 | 225.6 | 39.6 | 44.2 | 49.4 |
| 26 | 58.8 | 64.7 | 71.3 | 223.6 | 239.2 | 256 | 195.7 | 215.4 | 237 | 42 | 46.6 | 51.8 |
| 27 | 61.6 | 67.7 | 74.3 | 233.8 | 249.7 | 266.7 | 205.2 | 225.8 | 248.4 | 44.2 | 49 | 54.2 |
| 28 | 64.4 | 70.6 | 77.3 | 243.6 | 259.8 | 277.1 | 214.5 | 236.1 | 259.9 | 46.3 | 51.2 | 56.6 |
| 29 | 67 | 73.3 | 80.2 | 252.8 | 269.3 | 287 | 223.9 | 246.7 | 271.7 | 48.4 | 53.4 | 58.9 |
| 30 | 69.5 | 76 | 83 | 261.3 | 278.3 | 296.5 | 233.4 | 257.3 | 283.7 | 50.4 | 55.5 | 61.1 |
| 31 | 71.9 | 78.5 | 85.6 | 269.2 | 286.7 | 305.4 | 242.8 | 268 | 295.9 | 52.3 | 57.5 | 63.4 |
| 32 | 74.1 | 80.8 | 88.1 | 276.4 | 294.5 | 313.8 | 252 | 278.7 | 308.2 | 54.1 | 59.5 | 65.5 |
| 33 | 76.2 | 83 | 90.4 | 282.9 | 301.7 | 321.7 | 260.9 | 289.1 | 320.4 | 55.8 | 61.4 | 67.6 |
| 34 | 78 | 85 | 92.6 | 288.8 | 308.3 | 329 | 269.5 | 299.3 | 332.3 | 57.5 | 63.2 | 69.6 |
| 35 | 79.7 | 86.8 | 94.5 | 294 | 314.2 | 335.8 | 277.6 | 309 | 343.9 | 59 | 65 | 71.5 |
| 36 | 81.2 | 88.5 | 96.3 | 298.5 | 319.5 | 342 | 285.2 | 318.3 | 355.1 | 60.6 | 66.7 | 73.4 |
| 37 | 82.6 | 89.9 | 97.9 | 302.3 | 324.1 | 347.5 | 292.4 | 327.2 | 366 | 62 | 68.3 | 75.1 |
| 38 | 83.7 | 91.1 | 99.2 | 305.2 | 327.8 | 352.1 | 299.4 | 335.9 | 376.8 | 63.3 | 69.7 | 76.8 |
| 39 | 84.6 | 92.1 | 100.3 | 307.3 | 330.7 | 355.9 | 306.2 | 344.5 | 387.7 | 64.5 | 71.1 | 78.3 |
| 40 | 85.3 | 93 | 101.3 | 308.3 | 332.6 | 358.8 | 312.9 | 353.3 | 398.9 | 65.6 | 72.4 | 79.9 |
Indicator Notes
Usage Tips
All values are reference ranges (unit: mm). Individual differences exist, and measurements can be affected by fetal position. If your results fall into the "Low" or "High" range, consult an obstetrician for evaluation and avoid self-diagnosis.
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Are you unsure if the biparietal diameter (BPD), head circumference (HC), and other measurements on your ultrasound report are normal? Based on the Expert Consensus on Ultrasound Reference Values for Fetal Biometry, this tool provides standard millimeter-level reference ranges for key biological parameters—including BPD, HC, abdominal circumference (AC), and femur length (FL)—for fetuses from 10 to 40 weeks of gestation, helping you make an initial assessment of fetal development.
Q: Does a measurement outside the standard range indicate an abnormality?
A: Not necessarily. A high or low value simply means it deviates from the statistical average. It must be evaluated comprehensively alongside other clinical indicators. If you notice any anomalies, please consult a medical professional.
Q: What is the unit of measurement for these parameters?
A: All parameters are measured in millimeters (mm).
The data provided by this tool are statistical reference values, and individual differences are common. Ultrasound measurements can be affected by fetal position and equipment accuracy. These results cannot replace a professional medical diagnosis. Please seek medical advice promptly if you notice abnormal indicators.
Obstetrician's Advice: Focus on the correlation between parameters (e.g., BPD and HC should be evaluated together for head development). A typical example is the standard values at 20 weeks of gestation: BPD 47±4mm, HC 175±16mm, AC 150±16mm, FL 32±3mm. Comparing data across consecutive gestational weeks is more clinically meaningful than a single measurement.
