Fetal Growth Calculator

Hadlock Sonographic Biometry & Fetal Growth Standards

In maternal-fetal medicine, Estimated Fetal Weight (EFW) is calculated using regression algorithms developed by Dr. Frank Hadlock:

• Hadlock 4-Parameter Formula (Measurements in cm):

$$\log_{10}(\text{EFW}) = 1.3596 + (0.0064 \times \text{HC}) + (0.0424 \times \text{AC}) + (0.174 \times \text{FL}) + (0.00061 \times \text{BPD} \times \text{AC}) - (0.00386 \times \text{AC} \times \text{FL})$$

• Key Biometric Parameters:

• BPD (Biparietal Diameter): Width of the fetal head from temple to temple.

• HC (Head Circumference): Outer perimeter around the fetal skull.

• AC (Abdominal Circumference): Single most sensitive parameter for fetal liver glycogen reserves and soft tissue growth.

• FL (Femur Length): Length of the thigh bone, used to estimate total crown-to-heel length.

• Clinical Growth Categories:

• SGA (Small for Gestational Age): EFW $< 10\text{th percentile}$ (requires Doppler umbilical artery assessment).

• AGA (Appropriate for Gestational Age): EFW between $10\text{th and } 90\text{th percentile}$.

• LGA (Large for Gestational Age): EFW $> 90\text{th percentile}$ (risk of shoulder dystocia and gestational diabetes).

How to Use This Calculator

Enter Gestational Age (Weeks), Biparietal Diameter (BPD in mm), Head Circumference (HC in mm), Abdominal Circumference (AC in mm) into the input fields and the calculator will instantly compute Estimated Fetal Weight (EFW), Fetal Weight (Lbs & Oz). All calculations happen in real time — no submission or page reload required. You can adjust any input value and see the result update immediately.

Understanding Your Result

The Fetal Growth result gives you a precise, calculated value based on the inputs you provide. Compare your result against published benchmarks from WHO, CDC, and NIH to assess where you stand. A single calculation is a useful starting point, but tracking this metric over time — as inputs change — gives you a much more complete picture.

Practical Application

The Fetal Growth is most useful when you have specific, real-world data to enter. For example: enter your actual Gestational Age (Weeks) to calculate your estimated fetal weight (efw). The result helps health-conscious individuals, patients, and caregivers make informed decisions about tracking health metrics and understanding clinical reference ranges. This calculator is trusted by professionals and individuals alike because it follows the exact formulas validated by WHO, CDC, and NIH.

Accuracy Notes and Limitations

These results are screening estimates. Always consult a licensed healthcare provider before making changes to diet, medication, or exercise. The accuracy of any calculator is limited by the quality of the inputs provided. Double-check your units before entering values — unit errors are the most common source of incorrect results. For critical decisions, cross-reference with at least one additional source or professional consultation.

Frequently Used With

This calculator is often used alongside other health tools to build a complete analytical picture. Combining multiple related calculations provides stronger evidence for decisions than relying on any single metric. Browse the Health category to find complementary calculators for your specific use case.