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Pregnancy Weight Gain Calculator

Find your recommended total pregnancy weight gain range based on your pre-pregnancy BMI, using Institute of Medicine guidelines.

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in
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Result

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Pre-Pregnancy BMI Category
Normal weight
Recommended Total Gain25-35 lbs
Rough Gain So Far (Week 20)0-0 lbs

Based on IOM (Institute of Medicine) guidelines. Actual healthy weight gain varies by individual and pregnancy (e.g. twins).

This is an estimate for informational purposes only and is not medical advice. Consult a healthcare provider.

How to Calculate & Formula Details

Mathematical Model FormulaRecommended total gain by pre-pregnancy BMI category (IOM guidelines): Underweight 28-40 lbs, Normal 25-35 lbs, Overweight 15-25 lbs, Obese 11-20 lbs.

The Institute of Medicine (IOM) publishes recommended total pregnancy weight gain ranges based on a person's BMI before pregnancy, since a healthy amount of weight gain differs depending on starting weight.

Why Pre-Pregnancy BMI Matters

Someone who starts pregnancy underweight is generally advised to gain more than someone who starts overweight, to support healthy fetal development while managing maternal health risks.

Frequently Asked Questions

Does this apply to twin pregnancies?

No, these ranges are for singleton pregnancies. Recommended weight gain for twin or multiple pregnancies is higher and should be discussed with your OB-GYN.

What if I am gaining faster or slower than recommended?

Some variation is normal, especially early or late in pregnancy. Consistently gaining well above or below the recommended range is worth discussing with your healthcare provider.

Is the "gain so far" estimate exact?

No, it uses a simplified linear pacing model. Actual healthy weight gain is typically slower in the first trimester and faster in the second and third, so use it as a rough guide only.

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