There are several recommendations for pregnancy weight gain and BMI changes. The recommendations used the most was established by the Institute of Medicine (IOM) and by the American Congress of Obstetrics and Gynecology.


Institute of Medicine Weight Gain Recommendations for Pregnancy

Prepregnancy Weight Category Body Mass Index* Recommended  Range of Total Weight (lb) Recommended Rates of Weight Gain† in the Second and Third Trimesters (lb) (Mean Range [lb/wk])
Underweight Less than 18.5 28–40 1 (1–1.3)
Normal Weight 18.5–24.9 25–35 1 (0.8–1)
Overweight 25–29.9 15–25 0.6 (0.5–0.7)
Obese (includes all classes) 30 and greater 11–20 0.5 (0.4–0.6)
*Body mass index is calculated as weight in kilograms divided by height in meters squared or as weight in pounds multiplied by 703 divided by height in inches.
†Calculations assume a 1.1–4.4 lb weight gain in the first trimester.
Modified from Institute of Medicine (US). Weight gain during pregnancy: reexamining the guidelines. Washington, DC. National Academies Press; 2009. ©2009 National Academy of Sciences.

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