Gestational Weight Gain

IOM 2009 recommendations by pre-pregnancy BMI. Computes expected range at the current gestational age and flags actual gain as on-track, below, or above recommendation.

Reviewed by Pooja V. Menon, Registered Dietitian · Last updated Apr 20, 2026

Pre-pregnancy BMI (kg/m²)

Pregnancy type

Gestational age (weeks)

Weight gained so far (kg)

IOM 2009 recommendations

Pre-pregnancy BMI	Total gain (singleton)	Rate 2nd / 3rd trimester	Total gain (twins, provisional)
Underweight (< 18.5)	12.5 – 18 kg	0.44 – 0.58 kg/wk	insufficient data
Normal (18.5 – 24.9)	11.5 – 16 kg	0.35 – 0.50 kg/wk	17 – 25 kg
Overweight (25 – 29.9)	7 – 11.5 kg	0.23 – 0.33 kg/wk	14 – 23 kg
Obese (≥ 30)	5 – 9 kg	0.17 – 0.27 kg/wk	11 – 19 kg

First-trimester gain of roughly 0.5–2 kg is assumed across all groups; the per-week rate applies from week 14 onward.

Sources

Institute of Medicine (US) and National Research Council. Weight Gain During Pregnancy: Reexamining the Guidelines. Washington DC: National Academies Press, 2009.
ACOG Committee Opinion No. 548. Weight Gain During Pregnancy. Obstet Gynecol 2013;121:210–2 (reaffirmed 2020).