Pregnancy Weight Gain Calculator
IOM Weight Gain Guidelines
Enter your pre-pregnancy height and weight to see your recommended total weight gain range for a singleton pregnancy.
Parameters
Total Recommended Gain
Understanding IOM Pregnancy Weight Gain Guidelines
The Institute of Medicine (IOM, now the National Academy of Medicine) publishes weight-gain guidelines based on pre-pregnancy BMI category, since starting weight status significantly affects healthy gain targets for a singleton pregnancy.
BMI-Based Ranges
Underweight individuals are advised to gain more total weight, while individuals in a higher starting BMI category are advised to gain less.
Weekly Gain Rate
Most weight gain happens in the 2nd and 3rd trimesters — the 1st trimester typically involves only 1-4.5 lbs (0.5-2 kg) total.
Singleton Pregnancies Only
These guidelines apply to a single baby — twin and multiple pregnancies have separate, higher weight-gain recommendations.
Individualized Care
Your provider may adjust these targets based on your specific health history, prior pregnancies, or pregnancy complications.
IOM Weight Gain Guidelines (Singleton Pregnancy)
| Pre-Pregnancy BMI | Total Recommended Gain | 2nd/3rd Trimester Rate |
|---|---|---|
| Underweight (<18.5) | 28-40 lbs (12.5-18 kg) | ~1 lb/week (0.44-0.58 kg/week) |
| Normal (18.5-24.9) | 25-35 lbs (11.5-16 kg) | 0.8-1 lb/week (0.35-0.5 kg/week) |
| Overweight (25-29.9) | 15-25 lbs (7-11.5 kg) | 0.5-0.7 lb/week (0.23-0.33 kg/week) |
| Obese (30+) | 11-20 lbs (5-9 kg) | 0.4-0.6 lb/week (0.17-0.27 kg/week) |
Important Limitations
- General population guidelines: Individual needs vary based on health history, activity level, and how the pregnancy is progressing.
- Singleton only: These ranges don't apply to twin or higher-order multiple pregnancies.
- BMI shares BMI's limitations: Pre-pregnancy BMI doesn't account for muscle mass or frame size.
Key Takeaways
- Starting BMI shapes the target. Recommended total gain decreases as pre-pregnancy BMI category increases.
- Most gain happens later. The first trimester typically involves minimal weight change compared to the 2nd and 3rd.
- These are ranges, not strict targets. Healthy pregnancies can vary within (and sometimes outside) these guidelines.
- Consult your provider. IOM ranges are population guidelines — your doctor or midwife will adjust your personal target based on your health history and any pregnancy complications.