Calculadora de Ganho de Peso na Gravidez
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
IOM 2009: faixas por IMC pré-gestacional
About this calculator
The Pregnancy Weight Gain Calculator helps expectant mothers determine the ideal weight gain range during pregnancy, based on the 2009 Institute of Medicine (IOM) guidelines. It uses the pre-pregnancy Body Mass Index (BMI) to classify women as underweight, normal weight, overweight, or obese, each with specific total gain and weekly rate recommendations for the second and third trimesters.
To use it, simply enter your pre-pregnancy weight and height to calculate your BMI. The tool then applies the IOM table, which defines total gain ranges (in kg) and weekly gain rates (in kg/week) starting from the second trimester. For example, a woman with normal BMI (18.5-24.9) should gain 11.5-16 kg total, with 0.35-0.50 kg per week. This helps track progress and avoid excessive or insufficient gain.
Use this calculator early in prenatal care to set realistic weight gain goals. It is useful for pregnant women, nutritionists, and obstetricians to monitor progress. Remember that IOM recommendations are for singleton pregnancies; for multiple gestations or specific conditions, consult your doctor. Proper weight gain reduces risks of complications such as gestational diabetes, preeclampsia, and preterm birth.
Important cautions: use your pre-pregnancy BMI, not current. If you don't know your exact pre-pregnancy weight, try to estimate from records. This calculator provides a general reference, but each pregnancy is unique. Factors like age, height, and overall health matter. Always discuss results with your healthcare provider for a personalized plan.
Frequently asked questions
What if I don't know my exact pre-pregnancy weight?
Try to estimate from medical records, photos, or memory. If not possible, use your weight at the first prenatal visit as an approximation, but accuracy will be lower.
Do recommendations change for twin pregnancies?
Yes, for multiple gestations the gain ranges are different. Consult your doctor for specific guidance, as this calculator follows IOM for singleton pregnancy.
Can I use the calculator if I am overweight?
Yes, the calculator includes overweight and obese categories. Women with BMI over 30 should gain 5-9 kg total, with a lower weekly rate. Medical supervision is essential.
Is weight gain the same in all trimesters?
No. In the first trimester, gain is small (0.5-2 kg total). From the second trimester, the weekly rate varies by BMI. The calculator shows the recommended rate for the second and third trimesters.
What if I gain weight outside the recommended range?
Don't worry, this is common. Adjustments in diet and physical activity can help. Talk to your obstetrician or nutritionist to assess your individual situation.