Pregnancy Weight Gain Calculator
Based on your pre-pregnancy BMI and current week, see your recommended total weight gain and whether your gain so far is below, within or above the guideline band.
IOM guidance based on pre-pregnancy BMI. Your provider tailors this to you - never aim to lose weight in pregnancy without medical advice.
How the guideline works
The Institute of Medicine (2009) sets recommended total gain by pre-pregnancy BMI: underweight 28-40 lb, normal 25-35, overweight 15-25, obese 11-20 (singleton). We also estimate the expected gain band for your current week.
First trimester: about 1-4.4 lb total by week 13
After week 13: ~0.8-1.0 lb/week (normal BMI), less if higher BMI
Source: IOM/NRC "Weight Gain During Pregnancy" (2009).
Frequently asked questions
Where does pregnancy weight go?
The baby is only part of it. Gain also includes the placenta, amniotic fluid, extra blood and fluid, larger breasts and uterus, and some fat stores for feeding.
Should I lose weight while pregnant?
Weight loss in pregnancy is generally not recommended without medical supervision, even at a higher starting BMI. Follow your provider's guidance.
How much should twins add?
Twin pregnancies have higher recommended ranges. This tool switches to the IOM twin guidance when you tick the twins box.
What if I am gaining fast in the third trimester?
Some acceleration is normal, but sudden gain with swelling can signal a problem. Contact your provider if you are worried.
Medical disclaimer: This calculator is for general information and education only. It is an estimate, not medical advice, diagnosis or treatment. Always talk to your doctor or midwife about your health and any decisions.