It uses validated IOM and CDC equations and provides an accurate educational reference, but it is not a substitute for medical care. Always confirm trends with your healthcare provider.
Pregnancy Tracking Tool
Pregnancy Weight Gain Calculator
Track healthy pregnancy weight gain based on Institute of Medicine (IOM) guidelines. Works for both singleton and twin pregnancies.
The Pregnancy Weight Gain Calculator estimates a schedule for healthy weight gain based on guidelines from the Institute of Medicine. It first determines your pre-pregnancy BMI, then applies the IOM's recommended total weight gain range for your category.
The model assumes gradual gain during the first trimester, then a steady weekly increase through the second and third trimesters, producing a realistic "slow-then-steady" curve.
Pregnancy Weight Gain Calculator
Estimates healthy weight gain based on Institute of Medicine guidelines.
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How This Calculator Works
This calculator follows IOM and CDC guidelines to estimate healthy pregnancy weight gain by week:
- Calculate BMI: Using your pre-pregnancy height and weight
- Apply IOM guidelines: Recommendations vary by BMI category
- Adjust for twins: Twin pregnancies require higher weight gain
- Track progress: Compare your current weight to the target range
Chart Guide: The pink shaded area between the blue and red lines represents the recommended weight range, while the orange dot indicates your current weight.
Understanding Your Result
Within the Range
You're tracking well. Continue balanced nutrition, hydration, and moderate activity. Small weekly variations are expected — focus on the overall upward trend.
Below the Range
This may occur in early pregnancy due to nausea or low appetite. Your provider can help ensure your baby's growth stays on track.
Above the Range
Slight excess is common, but persistent over-gain may increase risks such as gestational diabetes. Review your nutrition with your provider.
Guidelines Behind the Math
The Institute of Medicine (IOM) provides the most widely accepted framework for gestational weight gain. These recommendations balance the mother's nutritional needs with optimal fetal growth and long-term health outcomes.
These guidelines were developed by analyzing pregnancy outcomes in over 120,000 births, correlating maternal gain with rates of preterm birth, fetal growth restriction, and postpartum recovery.
Singleton Pregnancy Guidelines (IOM, 2009)
| BMI Category | BMI Range | Total Weight Gain |
|---|---|---|
| Underweight | < 18.5 | 28–40 lbs (12.5–18 kg) |
| Normal Weight | 18.5–24.9 | 25–35 lbs (11.5–16 kg) |
| Overweight | 25–29.9 | 15–25 lbs (7–11.5 kg) |
| Obese | ≥ 30 | 11–20 lbs (5–9 kg) |
Twin Pregnancy Guidelines (IOM, 2009)
| BMI Category | BMI Range | Total Weight Gain |
|---|---|---|
| Underweight | < 18.5 | 50–62 lbs |
| Normal Weight | 18.5–24.9 | 37–54 lbs (17–25 kg) |
| Overweight | 25–29.9 | 31–50 lbs (14–23 kg) |
| Obese | ≥ 30 | 25–42 lbs (11–19 kg) |
For Surrogates
Maintaining a healthy, steady weight gain during pregnancy supports both your own comfort and the baby's development.
Every pregnancy is unique. Small variations are normal. If your result falls slightly outside the recommended range, keep open communication with your doctor and your Ivy Surrogacy coordinator.
Our team is here to provide encouragement, resources, and guidance whenever you need them.
For Intended Parents
Understanding your surrogate's pregnancy progress helps you stay emotionally connected to the journey and your growing baby.
This calculator gives you a simple, science-based way to visualize how a healthy pregnancy typically progresses week by week.
At Ivy Surrogacy, we believe in transparency and communication—keeping intended parents informed and reassured every step of the way.
Pregnancy Weight Gain: Frequently Asked Questions
1. Is this calculator medically accurate?
2. Why do my results differ from other calculators?
Some tools assume a fixed first-trimester gain (e.g., +2 lb), while others model it linearly. This calculator uses a realistic, evidence-based curve for smoother transitions.
3. What if I start pregnancy underweight or overweight?
That's precisely why we adjust by BMI. Underweight individuals need more total gain for fetal development, while overweight individuals typically need less.
4. How much should I gain if I'm carrying twins?
Twin pregnancies require substantially higher caloric intake and nutrient support. The calculator automatically uses IOM twin guidelines.
5. Can I switch between US and metric units?
Yes. All fields and results are synced; switching units automatically converts and recalculates your numbers.
6. Is small weight loss early in pregnancy normal?
Yes, mild loss from morning sickness or appetite changes in the first trimester is common. The key is regaining and following an upward trend later.
7. What if I'm outside the range?
Being slightly above or below the band is common. Extreme deviations or sudden changes should be discussed with your provider for personalized evaluation.
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Ready to Begin Your Surrogacy Journey?
Whether you're looking to become a surrogate or start your family through surrogacy, we're here to guide you every step of the way.
This calculator provides educational estimates only and should not be considered medical advice. Results may vary based on individual circumstances. Always consult with your healthcare provider for personalized medical guidance.