🤰 What Is a Pregnancy Weight Gain Calculator?

A Pregnancy Weight Gain Calculator estimates how much weight you should gain during your pregnancy based on your pre-pregnancy BMI, following CDC and 2009 Institute of Medicine guidelines. It also shows how your weight gain rate should progress per trimester, Merckmanuals.com+7cdc gov+7thebump.com+77.

📊 How It Works

You enter your pre-pregnancy weight/height to calculate your BMI category (underweight, normal, overweight, or obese).
Provide your current week of pregnancy and current weight.
The calculator outputs:
- Target total weight gain range
- Ideal weekly gain in the 2nd and 3rd trimesters
- How do you compare to the recommended pace

These follow evidence-based guidelines proven to support maternal and neonatal health.

🗓 Recommended Weight Gain by BMI

According to the CDC:

mermaidCopyEditbar
  title Total Pregnancy Weight Gain by Pre-pregnancy BMI
  "Underweight": 28–40 lbs
  "Normal": 25–35 lbs
  "Overweight": 15–25 lbs
  "Obese": 11–20 lbs

(8 kg = ~17.6 lbs)

Extracted from CDC references cdc.gov+1cdc.gov+1 calculator.net merckmanuals.com+2en.wikipedia.org+2obgproject.com+2 en.wikipedia.org+4cdc.gov+4eatingwell.com+4.

Second/third trimester gain rates:

Normal & underweight: about 1 lb/week
Overweight: 0.6 lb/week
Obese: 0.5 lb/week merckmanuals.com+2nap.nationalacademies.org+2en.wikipedia.org+2

📈 Weekly Weight Gain Chart

mermaidCopyEditline
  title Weekly Weight Gain During Trimester
  x-axis Pregnancy Week
  y-axis Cumulative Gain (lbs)
  12 : 2
  20 : Normal range
  30 : Midpoint gained
  40 : Within total

This visual helps track if you’re ahead, behind, or on target.

✅ Why Track Weight Gain?

🩺 Supports healthy fetal growth
👶 Reduces the risk of macrosomia, gestational diabetes, or undernutrition
📉 Helps avoid postpartum weight retention
📅 Guides caloric/nutrition planning: +340 kcal/day in 2nd trimester, +450 kcal/day in 3rd trimester., om+15cdc. +15thebump.com+15nam. +15obgproject.com+5acog +5calculatorr.net+5
📖 Enables evidence-based care and guidance

⚠️ Special Considerations

Twin/multiple pregnancies require higher gain targets (e.g., normal-BMI twins: 37–54 lbs) obgproject.com+3merckmanuals.com+3mayoclinic.org+3
BMI 30+ (Obese): Limited research but recommended gain is 11–20 lbs; some experts advise even less merckmanuals.com+10mayoclinic.org+10eatingwell.com+10
Monitor trend, not single measurements—crossing two percentile lines upwards or downwards should trigger medical review cdc.gov+15cdc.gov+15nap. nationalacademies.org+15.org+15

🔗 Related Internal Tools

Pregnancy Due Date Calculator
Pregnancy Weight Gain Tracker PDF (future resource)
All‑in‑One Pregnancy Calculator

🌐 Trusted External References

CDC – Pregnancy Weight Gain Guidelines thebump.com+15cdc.gov+15cdc.gov+15
Mayo Clinic – Healthy Pregnancy Weight Gain mayoclinic.org
Merck Manuals – Weight Gain Recommendations merckmanuals.com+1nap. nationalacademies.org+1.org+1

These amplify credibility and transparency.

📝 Diet & Exercise Tips

Follow balanced diets—whole grains, fruits, lean proteins, milk, eatingwell.com
Aim for 150 minutes of moderate exercise weekly, unless advised otherwise cdc gov+1en. wikipedia.org+1
Avoid strict dieting—restricting weight can harm the baby and increase the risk cdc.gov+12parents.com+12self.com+12