Pregnancy Weight Gain Calculator
Calculate your recommended weight gain during pregnancy based on IOM guidelines
Your weight before becoming pregnant
Enter to see how your gain compares to recommendations
Recommended Total Weight Gain
-
Twin Pregnancy •
Your Weight Gain Progress
Current Weight Gain
Expected gain at week :
Weekly Gain Rate
-
/week (2nd/3rd trimester)
Weeks Remaining
Until week 40 (due date)
Remaining to Gain
-
to reach goal
Pregnancy Progress
You are in week •
IOM Weight Gain Guidelines
| BMI Category | BMI Range | Total Gain (lbs) | Weekly Rate |
|---|---|---|---|
Source: Institute of Medicine (IOM) 2009 Guidelines, endorsed by ACOG
Where Does the Weight Go?
👶
Baby
7-8 lbs
💧
Amniotic Fluid
2 lbs
❤️
Blood Volume
4 lbs
🏠
Uterus
2 lbs
🍼
Breast Tissue
2 lbs
🫀
Placenta
1.5 lbs
💪
Fat Stores
5-9 lbs
💦
Body Fluids
4 lbs
If you like this calculator
Please help us simply by sharing it. It will help us a lot!
Related Calculators
Other calculators you might find useful.
Calories Burned Pilates Calculator
Calculate how many calories you burn during different Pilates exercises based on type, level, and intensity.
Ovulation Calculator
Predict your fertile window and ovulation date to maximize your chances of conception
Calories Burned Dancing Calculator
Calculate how many calories you burn while dancing based on dance style, duration, and body weight.
Calories Burned Standing Calculator
Calculate how many calories you burn while standing based on your weight, duration, and activity type.
Geriatric BMI Calculator
Calculate BMI with age-adjusted categories for adults 65 years and older
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) to know how many calories your body needs at rest.
About Pregnancy Weight Gain Calculator
The Pregnancy Weight Gain Calculator helps expectant mothers determine healthy weight gain targets throughout pregnancy. Using guidelines from the Institute of Medicine (IOM) and American College of Obstetricians and Gynecologists (ACOG), this tool provides personalized recommendations based on your pre-pregnancy BMI.
Why Weight Gain Matters During Pregnancy
Healthy weight gain during pregnancy supports:
- Proper fetal growth and development
- Adequate nutrient stores for breastfeeding
- Reduced risk of pregnancy complications
- Easier postpartum weight loss
IOM Recommended Weight Gain Guidelines
| Pre-Pregnancy BMI | Category | Recommended Gain (lbs) | Weekly Gain 2nd/3rd Trimester |
|---|---|---|---|
| Under 18.5 | Underweight | 28-40 lbs | 1.0-1.3 lbs/week |
| 18.5-24.9 | Normal Weight | 25-35 lbs | 0.8-1.0 lbs/week |
| 25.0-29.9 | Overweight | 15-25 lbs | 0.5-0.7 lbs/week |
| 30.0 or higher | Obese | 11-20 lbs | 0.4-0.6 lbs/week |
Source: Institute of Medicine (IOM) 2009 Guidelines, endorsed by ACOG
Weight Gain by Trimester
First Trimester (Weeks 1-12)
- Typical gain: 1-5 pounds total
- Some women may lose weight due to morning sickness
- Baby is very small (about 1 oz by week 12)
Second Trimester (Weeks 13-27)
- Steady weight gain begins
- Average: 1 pound per week for normal weight women
- Baby grows from 1 oz to about 2 lbs
Third Trimester (Weeks 28-40)
- Weight gain continues at similar rate
- Baby gains most weight during this period
- Some slowing of gain near due date is normal
Where Does the Weight Go?
During pregnancy, weight is distributed across:
| Component | Weight (lbs) |
|---|---|
| Baby | 7-8 lbs |
| Placenta | 1.5 lbs |
| Amniotic Fluid | 2 lbs |
| Uterus Enlargement | 2 lbs |
| Breast Tissue | 2 lbs |
| Blood Volume | 4 lbs |
| Maternal Fat Stores | 5-9 lbs |
| Fluids | 4 lbs |
| Total | 25-35 lbs |
Special Considerations
Twin Pregnancy
- Normal weight: 37-54 lbs
- Overweight: 31-50 lbs
- Obese: 25-42 lbs
Adolescent Pregnancy
- Young mothers may need to gain at the higher end of the range
- Consult healthcare provider for personalized guidance
Tips for Healthy Weight Gain
- Eat nutrient-dense foods - Focus on quality over quantity
- Stay active - Regular exercise supports healthy gain
- Monitor regularly - Track weight at prenatal visits
- Don't diet - Pregnancy is not the time to restrict calories
- Listen to your body - Eat when hungry, stop when satisfied
FAQ
Is it bad to gain too much weight?
Excessive weight gain increases risk of gestational diabetes, high blood pressure, and cesarean delivery.
What if I'm not gaining enough?
Insufficient weight gain can lead to low birth weight and preterm birth. Consult your healthcare provider.
Should I eat for two?
Not exactly. You only need about 340 extra calories per day in the second trimester and 450 in the third.
Disclaimer: This calculator provides general guidance based on IOM recommendations. Every pregnancy is unique. Always consult with your healthcare provider for personalized advice about weight gain during your pregnancy.
Understanding the Guidelines
Why BMI Matters
Your pre-pregnancy BMI determines your recommended weight gain because women with different starting weights have different nutritional needs during pregnancy.
First Trimester Gain
Weight gain is minimal in the first 12 weeks (1-5 lbs total). Some women even lose weight due to morning sickness. This is normal.
💡 Important Notes
- These are general guidelines - individual needs vary
- Rate of gain matters more than exact weekly numbers
- Sudden weight changes should be discussed with your doctor
- Focus on nutritious foods rather than restricting calories