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Provides the Institute of Medicine (IOM/NRC 2009) recommended total gestational weight gain and second/third-trimester rate based on pre-pregnancy body mass index (BMI). Categories: underweight (< 18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥ 30).
IOM 2009: Underweight 28–40 lb; Normal 25–35 lb; Overweight 15–25 lb; Obese 11–20 lb total (1st-trimester ~1–4.5 lb, then 2nd/3rd-trimester weekly rates per category)
Underweight: 28–40 lb (1.0–1.3 lb/wk); Normal: 25–35 lb (0.8–1.0 lb/wk); Overweight: 15–25 lb (0.5–0.7 lb/wk); Obese: 11–20 lb (0.4–0.6 lb/wk).
The IOM/NRC 2009 guidelines (weight gain during pregnancy) recommend total weight gain by pre-pregnancy BMI: underweight 28–40 lb, normal weight 25–35 lb, overweight 15–25 lb, and obese 11–20 lb, with 2nd/3rd-trimester rates of 1.0–1.3, 0.8–1.0, 0.5–0.7, and 0.4–0.6 lb/week respectively. The calculator returns the midpoint of the recommended total range for the entered BMI.
Specialty
ObstetricsCategory
Obstetrics & GynecologyDifficulty
Basic
Estimated Time
30 seconds
Version
1.0
Last Updated
2026-08-16
Formula
Keywords
Normal Range
Underweight: 28–40 lb (1.0–1.3 lb/wk); Normal: 25–35 lb (0.8–1.0 lb/wk); Overweight: 15–25 lb (0.5–0.7 lb/wk); Obese: 11–20 lb (0.4–0.6 lb/wk).
| Classification | Range |
|---|---|
Underweight pre-pregnancy BMI < 18.5 | 28–40 lb |
Normal weight pre-pregnancy BMI 18.5–24.9 | 25–35 lb |
Overweight pre-pregnancy BMI 25–29.9 | 15–25 lb |
Obese pre-pregnancy BMI ≥ 30 | 11–20 lb |
Provides the IOM/NRC 2009 recommended total gestational weight gain and second/third-trimester weekly rate based on pre-pregnancy BMI (underweight < 18.5, normal 18.5–24.9, overweight 25–29.9, obese ≥ 30).
IOM 2009 recommends total gains of 28–40 lb (underweight), 25–35 lb (normal), 15–25 lb (overweight), and 11–20 lb (obese), with 2nd/3rd-trimester rates of 1.0–1.3, 0.8–1.0, 0.5–0.7, and 0.4–0.6 lb/week respectively.
Appropriate gestational weight gain is associated with reduced risks of macrosomia, cesarean delivery, postpartum weight retention, and adverse neonatal outcomes; IOM targets guide routine prenatal counseling.
A woman with a pre-pregnancy BMI of 26 kg/m² (overweight) asks how much weight she should gain.
Inputs:
Recommended total gestational weight gain 15–25 lb (midpoint ~20 lb), at a 2nd/3rd-trimester rate of 0.5–0.7 lb/week.
The pre-pregnancy BMI (weight and height measured before conception or at the first prenatal visit) determines the recommended weight-gain range.
No. IOM 2009 also provides separate recommendations for twin gestations; this calculator applies to singleton pregnancies.
Disclaimer: This calculator is intended for educational and clinical decision support purposes only. Weight-gain recommendations should be individualized and integrated with nutrition counseling and clinical judgment.