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Pregnancy Weight Gain

Show the recommended total pregnancy weight gain range for a given pre-pregnancy BMI.

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What Pregnancy Weight Gain does

Guidance from the US Institute of Medicine, published in 2009 and still widely used, gives recommended total weight gain ranges based on pre-pregnancy BMI, with wider ranges for twins.

This looks up that guidance. Lower pre-pregnancy BMI corresponds to a higher recommended gain, and higher BMI to a lower one.

  • IOM recommended ranges by pre-pregnancy BMI category
  • Separate range for twin pregnancies

How to use Pregnancy Weight Gain

  1. 1

    Enter your pre-pregnancy BMI

    Calculate it with the BMI calculator using your weight before pregnancy, not your current weight.

  2. 2

    Indicate whether you are expecting twins

    The recommended range is higher for multiples.

  3. 3

    Discuss it with your clinician

    These are population guidelines; your own target may reasonably differ.

Limits and known behaviour

  • This is a lookup of published guidance, not a personal recommendation.
  • It gives the total gain for the whole pregnancy, not a week-by-week target, and gain is not expected to be evenly distributed across trimesters.
  • It requires your pre-pregnancy BMI, which this tool does not calculate.
  • The guidance is derived from US population data and other health systems publish different ranges.
  • It does not apply to triplets or higher-order multiples.
  • This is an estimate from a published formula, not a medical assessment. It cannot diagnose anything, and it is no substitute for advice from a clinician who knows your history.

Privacy and data handling

Runs entirely in your browser

  • Every figure you enter stays in this page. The figures you enter is not transmitted, logged or stored anywhere.
  • There is no account, no saved history and no autosave: reloading the page clears the form.

Site-wide data handling, including analytics and advertising, is described in the privacy policy.

Frequently asked questions

What if my gain is outside the recommended range?

Discuss it with your midwife or doctor rather than adjusting your diet on the strength of a lookup table. Both faster and slower gain are common and are assessed alongside everything else about the pregnancy.

Is weight gain steady through pregnancy?

No. Gain is typically small in the first trimester and greater in the second and third, so a mid-pregnancy figure should not be compared against the total range.