Pregnancy Weight Gain Calculator
Track and project your weight gain throughout pregnancy based on IOM guidelines. Ensure you are within a healthy range for you and your baby.
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Understanding Healthy Pregnancy Weight Gain
Gaining a healthy amount of weight during pregnancy is crucial for the well-being of both the mother and the baby. The recommended weight gain depends on a woman's pre-pregnancy Body Mass Index (BMI). This calculator helps you determine your recommended weight gain range and track your progress throughout your pregnancy.
Institute of Medicine (IOM) Guidelines
The guidelines for pregnancy weight gain are based on your pre-pregnancy BMI category. Our calculator first determines your BMI and then provides the corresponding recommended weight gain range from the Institute of Medicine (IOM).
Weight Gain Recommendations for a Singleton Pregnancy:
- Underweight (BMI < 18.5): 28–40 pounds (about 12.5–18 kg)
- Normal weight (BMI 18.5–24.9): 25–35 pounds (about 11.5–16 kg)
- Overweight (BMI 25.0–29.9): 15–25 pounds (about 7–11.5 kg)
- Obese (BMI ≥ 30.0): 11–20 pounds (about 5–9 kg)
For twin pregnancies, the recommended weight gain is higher. The calculator adjusts for this if you select the "twins" option.
How Weight is Distributed
The weight you gain isn't just "fat." It's distributed among various components essential for a healthy pregnancy. At term, the average distribution is roughly:
- Baby: ~7.5 pounds
- Placenta: ~1.5 pounds
- Amniotic fluid: ~2 pounds
- Increased breast tissue: ~2 pounds
- Increased blood volume: ~4 pounds
- Uterus growth: ~2 pounds
- Maternal fat stores: ~7 pounds
Rate of Weight Gain
Weight gain is not linear. It's typically slower in the first trimester and faster in the second and third.
- First Trimester (Weeks 1-12): A gain of 1 to 4.5 pounds is typical.
- Second & Third Trimesters: For a woman with a normal pre-pregnancy BMI, a gain of about 1 pound per week is recommended. The rate is slightly higher for underweight women and slightly lower for overweight and obese women.
Our calculator provides a week-by-week chart to help you visualize your progress against the recommended range.
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