Hadlock Peso Fetal Calculadora

The Hadlock formula is a method used to estimate fetal weight based on maternal weight and gestational age. This calculator provides a quick and accurate way to determine fetal weight during pregnancy.

What is the Hadlock Formula?

The Hadlock formula is an empirical equation used to estimate fetal weight during pregnancy. It was developed based on observations of fetal weights and maternal weights at different gestational ages.

The formula takes into account both maternal weight and gestational age to provide a more accurate estimate of fetal weight compared to using maternal weight alone.

Hadlock Formula

Fetal Weight (grams) = 1,000 + 2.5 × (Maternal Weight - 60 kg) + 0.005 × (Gestational Age - 20 weeks)²

Where:

Maternal Weight is in kilograms
Gestational Age is in weeks

Note

The Hadlock formula provides an estimate and should not replace professional medical advice. Actual fetal weight may vary based on individual factors.

How to Use This Calculator

Using the Hadlock Peso Fetal Calculadora is simple:

Enter your maternal weight in kilograms
Enter your gestational age in weeks
Click the "Calculate" button
Review the estimated fetal weight in grams

The calculator will display the estimated fetal weight based on the Hadlock formula. You can also view a chart showing the estimated fetal weight over time.

Interpreting Results

The estimated fetal weight provided by this calculator is based on average values. Here's how to interpret the results:

For a healthy pregnancy, the estimated fetal weight should be within the normal range for the given gestational age
Significantly lower or higher weights may indicate potential issues that should be discussed with a healthcare provider
The estimate becomes more accurate as the pregnancy progresses

Normal Fetal Weight Ranges by Gestational Age
Gestational Age	Normal Weight Range (grams)
20-24 weeks	500-1,000
25-29 weeks	1,000-1,500
30-34 weeks	1,500-2,000
35-39 weeks	2,000-2,500
40+ weeks	2,500-4,000

Limitations

While the Hadlock formula provides a useful estimate, it has some limitations:

It's based on average values and may not account for individual variations
It doesn't consider factors like multiple pregnancies or fetal growth patterns
Accuracy improves as the pregnancy progresses

For precise fetal weight measurements, ultrasound is the gold standard. This calculator should be used for general estimation purposes only.

FAQ

Is the Hadlock formula accurate for all pregnancies?

The Hadlock formula provides a general estimate and is most accurate for singleton pregnancies. It may not be as precise for multiple pregnancies or pregnancies with complications.

When should I use this calculator?

This calculator is most useful during the second and third trimesters when the estimate becomes more reliable. For early pregnancy, other methods may be more appropriate.

What if my estimated fetal weight is outside the normal range?

If your estimated fetal weight is significantly outside the normal range, it's important to discuss this with your healthcare provider. They may recommend additional monitoring or testing.