Fetal Weight Calculator
Professional pregnancy weight estimation tool
Important Medical Disclaimer
This tool is for educational purposes only and cannot replace professional medical advice, diagnosis, or treatment. Fetal weight calculations should always be interpreted by qualified healthcare professionals. Please consult with your healthcare provider for medical decisions and pregnancy care.
Fetal Weight Calculator
Fetal Growth Calculator
Calculation Formulas
Hadlock 4 (Recommended)
Most accurate formula using AC, FL, HC, and BPD measurements. Widely used in clinical practice with high accuracy.
Hadlock 3
Alternative Hadlock formula using AC, FL, and HC measurements. Good accuracy for most gestational ages.
Shepard Formula
Uses BPD and AC measurements. Simpler formula but may be less accurate in certain situations.
BPD + AC + FL
Three-parameter formula: weight = 1.07 × BPD³ + 0.3 × AC² × FL. Good for BPD-based calculations.
Fundal Height + AC
Simple formula: weight = FH × AC + 200. Used when ultrasound measurements are not available.
Growth Percentiles
WHO-based percentiles for fetal growth assessment. Compare measurements to population standards.
Frequently Asked Questions
What is a fetal weight calculator?
A fetal weight calculator is a medical tool that estimates the weight of an unborn baby using ultrasound measurements. It uses various formulas based on measurements like BPD (biparietal diameter), AC (abdominal circumference), FL (femur length), and HC (head circumference) to predict fetal weight. This tool is commonly used during pregnancy to monitor fetal growth and development.
What measurements are needed for fetal weight calculation?
The measurements needed depend on the formula used. Common measurements include: BPD (biparietal diameter) - the width of the baby's head, AC (abdominal circumference) - around the baby's abdomen, FL (femur length) - the length of the thigh bone, HC (head circumference) - around the baby's head, and FH (fundal height) - the height of the uterus. These measurements are typically obtained during routine ultrasound examinations.
Which formula is most accurate for fetal weight calculation?
The Hadlock 4 formula is generally considered the most accurate and widely used formula for fetal weight estimation. It uses multiple measurements (AC, FL, HC, BPD) and has been validated in numerous studies. However, accuracy can vary depending on gestational age, fetal position, and individual variations. All formulas have inherent limitations and should be interpreted by healthcare professionals.
How accurate are fetal weight calculations?
Fetal weight calculations have inherent limitations and accuracy varies. Generally, estimates are within 10-15% of actual birth weight in most cases. Accuracy tends to decrease in very large or very small fetuses, and in late pregnancy. Multiple factors can affect accuracy including fetal position, maternal factors, and measurement quality. These calculations should always be interpreted by qualified healthcare professionals.
When should fetal weight be calculated?
Fetal weight calculations are typically performed during routine ultrasound examinations, usually in the second and third trimesters. They are particularly important when monitoring fetal growth, assessing for growth restriction or macrosomia, planning delivery, or when there are concerns about fetal size. The timing and frequency should be determined by your healthcare provider based on your individual pregnancy.
What do growth percentiles mean?
Growth percentiles compare your baby's measurements to a reference population. For example, if your baby is at the 50th percentile, it means 50% of babies are smaller and 50% are larger. Percentiles between 10th and 90th are generally considered normal. Percentiles help identify if a baby is growing appropriately for gestational age and can help detect potential growth issues.
Should I be concerned if my baby's weight seems high or low?
Fetal weight estimates are just one piece of information and should not cause undue concern. Many factors can affect these calculations, and there's always a margin of error. If you have concerns about your baby's size or growth, discuss them with your healthcare provider. They will consider multiple factors including your medical history, pregnancy progress, and overall fetal well-being to provide appropriate guidance.
Can I use this calculator instead of medical advice?
No, this calculator is for educational and informational purposes only. It cannot and should not replace professional medical advice, diagnosis, or treatment. Fetal weight calculations should always be interpreted by qualified healthcare professionals who can consider your complete medical history, pregnancy progress, and other relevant factors. Always consult with your healthcare provider for medical decisions.
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