The Pregnancy Weight Gain Calculator estimates recommended total pregnancy weight-gain ranges from pre-pregnancy BMI and current pregnancy week. It uses broad BMI bands and a simple linear progress model through week 40.
Calculation method
The module assigns total recommended gain ranges by pre-pregnancy BMI: 12.5-18 kg below 18.5, 11.5-16 kg from 18.5 to 24.9, 7-11.5 kg from 25 to 29.9, and 5-9 kg at 30 or above. It estimates progress from week 13 through week 40, with an early 0.5 kg baseline.
Example
At 20 weeks with a pre-pregnancy BMI of 22, the calculator selects the 11.5-16 kg range and estimates the expected minimum and maximum reached so far using the module's progress fraction.
Questions
Does BMI determine the correct gain for every pregnancy?
No. BMI bands are a broad screening framework. Twins, medical history, nausea, nutrition, and clinician guidance can change appropriate targets.
Why is the early baseline 0.5 kg?
That is the fixed starting assumption in this calculator's progress model; it is not an individualized clinical target.
Should I try to hit the exact range?
Use it as context, not a prescription. Discuss weight change, nutrition, and symptoms with your maternity-care provider.
Health notice and limitations
This tool is educational and does not replace prenatal care. It does not model multiple pregnancies, edema, gestational conditions, fetal growth, or individualized recommendations.