Healthy pregnancy weight-gain ranges by pre-pregnancy BMI and trimester — Institute of Medicine guidelines. ✓ IOM guidelines
By pre-pregnancy BMI, per Institute of Medicine guidelines.
| Pre-pregnancy category | BMI | Total gain | Rate (2nd & 3rd trimester) | Twins |
|---|---|---|---|---|
| Underweight | Below 18.5 | 28–40 lb | 1.0–1.3 lb/week | 50–62 lb |
| Healthy weight | 18.5–24.9 | 25–35 lb | 0.8–1.0 lb/week | 37–54 lb |
| Overweight | 25.0–29.9 | 15–25 lb | 0.5–0.7 lb/week | 31–50 lb |
| Obese | 30.0 and above | 11–20 lb | 0.4–0.6 lb/week | 25–42 lb |
First-trimester gain is small for everyone — about 1–4.5 lb total. Most gain happens in the second and third trimesters at the weekly rate shown.
Recommended weight gain depends on your weight before pregnancy. A woman at a healthy pre-pregnancy BMI (18.5–24.9) is advised to gain about 25–35 pounds for a single baby, while someone who began underweight should gain more (28–40 lb) and someone overweight or obese less (11–25 lb). Gaining within your range supports your baby's growth while lowering the risk of complications for both of you.
Most of the gain comes in the second and third trimesters — often around a pound a week for a healthy-weight woman — while the first trimester adds only a few pounds. Carrying twins calls for more. To find your pre-pregnancy BMI category, use our BMI calculator, and track key dates with the pregnancy calculator and due date calculator.