👶 Estimated Fetal Weight (Hadlock)
UseEnter the four biometric measurements in centimeters; the tool returns EFW with a ±1 SD (7.5%) interval. Judg…
SourceISUOG Practice Guidelines: ultrasound assessment of fetal biometry and growth. Ultrasound Obstet Gy…
This-shift next steps
After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.
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Methodology · worked example, guidelines & full notes
The original paper reports 1 SD as 7.5%; error widens at the extremes of fetal size, with oligohydramnios, and at extreme gestational ages. (original synthesis · not guideline verbatim)
When to use
Enter the four biometric measurements in centimeters; the tool returns EFW with a ±1 SD (7.5%) interval. Judge SGA/LGA against a gestational-age growth curve, not absolute grams.
How it works
log10(EFW) = 1.3596 + 0.0064·HC + 0.0424·AC + 0.174·FL + 0.00061·BPD·AC − 0.00386·AC·FL (all in cm); EFW = 10^log10. Reported interval = EFW × 0.925 to × 1.075 (±1 SD; the original paper reports 1 SD as 7.5%).
Key points
- The original paper reports 1 SD as 7.5%; error widens at the extremes of fetal size, with oligohydramnios, and at extreme gestational ages. (original synthesis · not guideline verbatim)
- A common pitfall is entering measurements in millimeters — the formula expects centimeters, and mm input grossly overestimates weight.
- EFW is a point estimate; growth-restriction or macrosomia decisions require GA-specific percentiles and serial measurements, not a single weight.
References
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Biparietal diameter BPD | 9.0 cm |
|---|---|
| Head circumference HC | 32.0 cm |
| Abdominal circumference AC | 30.0 cm |
| Femur length FL | 6.5 cm |
→Estimated fetal weight2396g
- ±1 SD (7.5%) interval：2216 ~ 2575 g
Verification & sources · governance
FAQ
Frequently asked questions
- What are the limits and cautions when using Estimated Fetal Weight (Hadlock)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- Does Estimated Fetal Weight (Hadlock) upload patient data? Where is it calculated?
- Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
- How is Estimated Fetal Weight (Hadlock) calculated in practice? Can you show a worked example?
- Inputs: Biparietal diameter BPD 9.0 cm, Head circumference HC 32.0 cm, Abdominal circumference AC 30.0 cm, Femur length FL 6.5 cm → Result: Estimated fetal weight 2396 g（±1 SD (7.5%) interval: 2216 ~ 2575 g）