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Evidence-based pregnancy weight gain calculator following IOM guidelines. Track healthy weight gain by trimester based on your pre-pregnancy BMI with personalized recommendations.
Your baby accounts for about 7-8 pounds of your total pregnancy weight gain. This is the most important component of healthy weight gain.
Placenta (1-2 lbs), amniotic fluid (2 lbs), and increased blood volume (3-4 lbs) support your baby's growth and development.
Breast tissue (1-2 lbs), uterus growth (2 lbs), fat stores (6-8 lbs), and extra fluid (2-3 lbs) prepare your body for birth and breastfeeding.
This calculator provides general guidance based on IOM guidelines and should not replace professional medical advice. Every pregnancy is unique. Always consult your healthcare provider for personalized recommendations, especially if you have pre-existing conditions, are carrying multiples, or have concerns about your weight gain pattern.
This calculator and guide have been reviewed by Dr. Sarah Johnson, MD, a board-certified OB-GYN with 15+ years of experience in maternal-fetal medicine. Content is based on current IOM (Institute of Medicine) guidelines and peer-reviewed research.
Last Medical Review: 2025-12-24 | Next Review: March 2025
Our evidence-based pregnancy weight gain calculator helps you track healthy weight gain throughout your pregnancy following IOM (Institute of Medicine) guidelines. Enter your pre-pregnancy weight, height, current weight, and pregnancy week. The calculator determines your pre-pregnancy BMI, recommends total weight gain based on established medical guidelines, and shows whether your current weight gain is on track. You'll receive personalized recommendations for weekly weight gain rates and trimester-specific targets based on your individual BMI category.
The Institute of Medicine (IOM) provides evidence-based weight gain recommendations based on pre-pregnancy BMI:
Pregnancy weight gain follows a predictable pattern across the three trimesters:
Twin pregnancies require higher weight gain to support two babies. Recommendations: Normal weight women should gain 37-54 lbs (17-25 kg), overweight women 31-50 lbs (14-23 kg), and obese women 25-42 lbs (11-19 kg). Weekly gain should be 0.7-0.9 kg (1.5-2 lbs) after the first trimester. Twin pregnancies require closer monitoring and more frequent prenatal visits.
Understanding weight distribution helps you appreciate why weight gain is necessary:
Focus on nutrient-dense foods rather than "eating for two." You need only 340 extra calories daily in the second trimester and 450 in the third trimester. Choose whole grains, lean proteins, fruits, vegetables, dairy products, and healthy fats. Take prenatal vitamins with folic acid, iron, and calcium. Stay hydrated with 8-10 glasses of water daily. Avoid empty calories from sugary drinks, processed foods, and excessive sweets.
Regular exercise helps manage weight gain, reduces pregnancy discomfort, and prepares your body for labor. Aim for 150 minutes of moderate exercise weekly. Safe activities include walking, swimming, prenatal yoga, and stationary cycling. Avoid contact sports, activities with fall risk, and exercises lying flat on your back after the first trimester. Always consult your healthcare provider before starting any exercise program.
If you're gaining too much weight, don't diet or restrict calories. Instead, focus on healthy food choices, control portion sizes, limit sugary drinks and snacks, increase physical activity (with doctor approval), and track your eating patterns. Excessive weight gain increases risks of gestational diabetes, high blood pressure, cesarean delivery, and postpartum weight retention. Work with your healthcare provider for personalized guidance.
Inadequate weight gain may affect baby's growth and development. Increase calorie intake with nutrient-dense foods like nuts, avocados, whole milk, and nut butters. Eat frequent small meals throughout the day. Add healthy snacks between meals. Consider nutritional supplements if recommended by your doctor. Address any underlying issues like severe morning sickness, food aversions, or eating disorders with professional help.
After delivery, you'll immediately lose about 12-14 lbs (baby, placenta, amniotic fluid). Over the next 6-12 months, you'll gradually lose the remaining weight through breastfeeding (burns 300-500 calories daily), healthy eating, and exercise. Most women return to pre-pregnancy weight within 6-12 months, though this varies. Be patient with your body and focus on healthy habits rather than rapid weight loss. Avoid crash diets, especially if breastfeeding.
Contact your doctor if you experience sudden rapid weight gain (more than 2 lbs per week), significant weight loss, inability to gain weight despite adequate eating, severe morning sickness preventing eating, swelling in face or hands (may indicate preeclampsia), or concerns about your weight gain pattern. Regular prenatal visits allow your healthcare team to monitor your weight gain and address any concerns promptly.
Weight gain patterns vary by individual. Most women gain 1-4 lbs (0.5-2 kg) during the first trimester, though some may gain less or even lose weight due to morning sickness. Steady weight gain typically begins in the second trimester at a rate of 0.5-1 lb (0.2-0.5 kg) per week for normal-weight women, continuing through the third trimester. The rate varies based on your pre-pregnancy BMI category.
Excessive weight gain increases risks of gestational diabetes, high blood pressure, and delivery complications. Focus on nutritious foods, control portion sizes, stay physically active with doctor approval, and avoid empty calories. Never diet during pregnancy - consult your healthcare provider for personalized guidance.
Insufficient weight gain may affect baby's growth and development. Increase calorie intake with nutrient-dense foods, eat frequent small meals, add healthy fats like nuts and avocados, and consider nutritional supplements. Always consult your healthcare provider if you're concerned about inadequate weight gain.
After the first trimester, recommended weekly weight gain varies by pre-pregnancy BMI: Underweight: 0.5-0.6 kg (1-1.3 lbs), Normal weight: 0.4-0.5 kg (0.8-1 lb), Overweight: 0.2-0.3 kg (0.5-0.7 lbs), Obese: 0.2-0.3 kg (0.4-0.6 lbs). First trimester gain is typically minimal.
Weight distribution: Baby (7-8 lbs), Placenta (1-2 lbs), Amniotic fluid (2 lbs), Breast tissue (1-2 lbs), Blood supply (3-4 lbs), Fat stores (6-8 lbs), Uterus growth (2 lbs), Extra fluid (2-3 lbs). Total: 25-35 lbs for normal weight women.
Yes, it's common to lose 1-5 lbs in the first trimester due to morning sickness, nausea, and food aversions. As long as you're staying hydrated and eating when possible, this is usually not concerning. Contact your doctor if you're losing significant weight or can't keep food down.
Twin pregnancy weight gain recommendations: Underweight/Normal weight: 37-54 lbs (17-25 kg), Overweight: 31-50 lbs (14-23 kg), Obese: 25-42 lbs (11-19 kg). Twin pregnancies require more calories and closer monitoring. Weekly gain should be 0.7-0.9 kg (1.5-2 lbs) after first trimester.
No, dieting or restricting calories during pregnancy is not recommended, even if you're overweight. Focus on eating nutritious foods, controlling portions, staying active, and gaining within recommended ranges. Your baby needs adequate nutrition for healthy development. Consult your healthcare provider for safe weight management strategies.
First trimester: No extra calories needed. Second trimester: Add 340 calories/day. Third trimester: Add 450 calories/day. Twin pregnancy: Add 600 calories/day in second and third trimesters. Focus on nutrient-dense foods rather than empty calories.
Immediately after delivery, you'll lose about 12-14 lbs (baby, placenta, amniotic fluid). Over the next 6-12 months, you'll gradually lose the remaining weight through breastfeeding, healthy eating, and exercise. Most women return to pre-pregnancy weight within 6-12 months, though this varies individually.
Yes, breastfeeding burns 300-500 extra calories per day, which can help with postpartum weight loss. However, you need adequate nutrition for milk production. Combine breastfeeding with healthy eating and gradual exercise for safe, sustainable weight loss. Avoid crash diets as they can affect milk supply.
Evidence-Based Guidelines: This calculator uses recommendations from the Institute of Medicine (IOM) and American College of Obstetricians and Gynecologists (ACOG).
Medical Review: Content reviewed by Dr. Sarah Johnson, MD, Board-Certified OB-GYN with 15+ years of experience in maternal-fetal medicine and high-risk pregnancy management.
Sources: Institute of Medicine (US) and National Research Council (US) Committee to Reexamine IOM Pregnancy Weight Guidelines; Rasmussen KM, Yaktine AL, editors. Weight Gain During Pregnancy: Reexamining the Guidelines. Washington (DC): National Academies Press (US); 2009.
Last updated: 2025-12-24. We review and update our calculators regularly to ensure accuracy and alignment with current medical guidelines.