Pregnancy Weight Gain
Monitor your healthy progress based on clinical BMI guidelines.
1. Pre-pregnancy Stats
2. Current Status
Pregnancy Weight Gain Calculator
How much weight should you gain during pregnancy? The answer depends on your pre-pregnancy BMI. This calculator uses the Institute of Medicine (IOM) guidelines to give you a personalized, trimester-by-trimester weight gain target.
How to Use This Calculator
- Enter your pre-pregnancy weight and height to calculate starting BMI.
- Enter your current pregnancy week.
- Click Calculate to see your recommended total weight gain range and week-by-week targets.
IOM Recommended Pregnancy Weight Gain
- Underweight (BMI < 18.5): 28–40 lbs (12.5–18 kg)
- Normal weight (BMI 18.5–24.9): 25–35 lbs (11.5–16 kg)
- Overweight (BMI 25–29.9): 15–25 lbs (7–11.5 kg)
- Obese (BMI ≥ 30): 11–20 lbs (5–9 kg)
- Twin pregnancy (normal weight): 37–54 lbs (17–25 kg)
Where Does Pregnancy Weight Come From?
- Baby: ~7–8 lbs
- Placenta: ~1–2 lbs
- Amniotic fluid: ~2 lbs
- Uterus growth: ~2 lbs
- Breast tissue: ~1–3 lbs
- Blood volume increase: ~3–4 lbs
- Fluid/fat stores: ~5–9 lbs
Common Mistakes to Avoid
- Dieting aggressively to avoid weight gain — Restricting calories too severely during pregnancy can harm fetal development. Focus on nutrient quality, not minimal weight gain.
- Gaining too much in the first trimester — Most gain (0.5–1 lb/week) happens in the second and third trimesters. First-trimester gain is typically 1–5 lbs total.
- Using pre-pregnancy BMI based on current weight — Always use your pre-pregnancy weight (before conception) for the baseline BMI calculation.
Frequently Asked Questions
What if I gain more than recommended?
Excessive gestational weight gain is associated with higher risk of gestational diabetes, C-section, postpartum weight retention, and childhood obesity in the baby. Talk to your OB about appropriate adjustments.
What if I gain less than recommended?
Inadequate weight gain increases risk of preterm birth and low birth weight. This is especially concerning in underweight women. Work with your provider to ensure adequate nutrition.
How much of pregnancy weight is retained after birth?
Most women lose 10–15 lbs immediately after delivery (baby, placenta, amniotic fluid). The remaining weight is typically lost over 6–12 months with healthy eating and moderate activity.
Conclusion
Pregnancy weight gain within the recommended range supports a healthy baby and easier postpartum recovery. Use this calculator as a guide and review your progress at each prenatal appointment.
Related: Pregnancy Calculator | BMI Calculator | Calorie Calculator | Due Date Calculator
Important Note
Every pregnancy is unique. These are general guidelines based on clinical averages. Always follow the specific weight goals set by your midwife or doctor.
