Weight Gain Chart
Trimester Weight Gain Breakdown
Weekly Weight Log
IOM Weight Gain Recommendations by BMI
| BMI Category | BMI Range | Total Gain | Weekly Gain (2nd & 3rd Tri) |
|---|---|---|---|
| Underweight | < 18.5 | 28–40 lbs | 1.0–1.3 lbs/wk |
| Normal | 18.5–24.9 | 25–35 lbs | 0.8–1.0 lbs/wk |
| Overweight | 25.0–29.9 | 15–25 lbs | 0.5–0.7 lbs/wk |
| Obese | ≥ 30.0 | 11–20 lbs | 0.4–0.6 lbs/wk |
Where Does Pregnancy Weight Gain Go?
This calculator provides general estimates based on IOM (Institute of Medicine) guidelines and is not a substitute for professional medical advice. Every pregnancy is unique. Your healthcare provider may recommend different weight gain targets based on your individual health, medical history, and pregnancy complications. Always consult your doctor or midwife for personalized guidance.
How Much Weight Should You Gain During Pregnancy?
Pregnancy weight gain is one of the most common concerns for expectant mothers. Gaining the right amount of weight supports your baby's healthy development while reducing your risk of pregnancy complications. The Institute of Medicine (IOM) provides evidence-based guidelines based on your pre-pregnancy Body Mass Index (BMI).
Why Pre-Pregnancy BMI Matters
Your BMI before pregnancy is the primary factor in determining how much weight you should gain. BMI is calculated by dividing your weight in kilograms by your height in meters squared. Women who start pregnancy underweight need to gain more weight to ensure adequate nutrition for the baby, while women who start at a higher BMI are advised to gain less to reduce risks of gestational diabetes, preeclampsia, and cesarean delivery.
First Trimester Weight Gain
During the first trimester (weeks 1–12), weight gain is minimal — typically 1 to 5 pounds total regardless of BMI category. Some women even lose weight due to morning sickness, which is usually not a concern unless the loss is significant. The baby is very small during this period, and most caloric needs can be met by eating a normal, balanced diet without extra calories.
Second and Third Trimester Weight Gain
The majority of pregnancy weight gain occurs during the second and third trimesters when the baby is growing rapidly. During these weeks, steady, gradual weight gain is ideal. For normal-weight women, this means gaining about 1 pound per week. The rate varies by BMI category — underweight women should aim for slightly more, while overweight and obese women should aim for less.
Risks of Too Little or Too Much Weight Gain
Gaining too little weight during pregnancy increases the risk of delivering a low birth weight baby (under 5.5 lbs), preterm birth, and developmental delays. Gaining too much weight raises the risk of gestational diabetes, high blood pressure, preeclampsia, cesarean delivery, macrosomia (a larger-than-average baby), and difficulty losing weight after pregnancy.
- Too little gain: Low birth weight, preterm delivery, nutrient deficiencies
- Too much gain: Gestational diabetes, preeclampsia, macrosomia, difficult labor
Tips for Healthy Pregnancy Weight Gain
- Eat nutrient-dense foods — focus on fruits, vegetables, lean proteins, whole grains, and dairy
- You only need about 340 extra calories per day in the 2nd trimester and 450 in the 3rd trimester
- Stay active — most pregnant women can safely walk, swim, or do prenatal yoga
- Weigh yourself weekly at the same time of day for consistent tracking
- Talk to your healthcare provider if your weight gain is significantly above or below the recommended range