Pregnancy Weight Gain Calculator

See a recommended weight gain range for your stage of pregnancy, based on Institute of Medicine guidelines for your pre-pregnancy BMI.

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How the recommended range is set

The Institute of Medicine's guidelines set a total recommended weight gain range based on your pre-pregnancy BMI: roughly 28-40 lbs if underweight, 25-35 lbs at a normal weight, 15-25 lbs if overweight, and 11-20 lbs if obese (higher for twin pregnancies). Within that total, standard guidance calls for a modest 1-4 lb gain during the first trimester, followed by a fairly steady weekly rate through the rest of pregnancy.

About the week-by-week schedule

The table spreads the total recommended range across all 40 weeks using that same two-phase pattern — a light first-trimester ramp, then a steady rate to delivery. It's a smoothed approximation of the published guidance meant to show the overall shape of a healthy trajectory, not a clinically exact weekly target — actual recommended pacing can vary somewhat by source and by individual.

These are population-level guidelines, not a strict target. Actual healthy weight gain varies by individual — always follow your own care provider's guidance over any calculator.

Common questions

What if my current weight is outside the recommended range?

It's common, and not automatically a cause for concern — many factors affect weight gain during pregnancy. Bring it up with your care provider, who can assess your specific situation.

Why is the twin-pregnancy range higher?

Carrying twins means more total fetal weight, more placental tissue, and more amniotic fluid, so the Institute of Medicine's recommended ranges for twin pregnancies run notably higher than for a single baby.

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