Calculate healthy weight gain during pregnancy based on your pre-pregnancy BMI and current pregnancy stage. Get personalized recommendations following Institute of Medicine guidelines.
Healthy weight gain during pregnancy is essential for both maternal and fetal health. The amount of weight you should gain depends on your pre-pregnancy BMI, whether you're carrying multiples, and your individual health circumstances. Our calculator follows the Institute of Medicine (IOM) guidelines to provide personalized recommendations.
Weight gain during pregnancy supports the growth of the fetus, placenta, increased blood volume, breast tissue, and energy stores needed for breastfeeding. Gaining too little or too much weight can lead to complications for both mother and baby.
| Pre-pregnancy BMI | BMI Category | Total Weight Gain (Single Baby) | Total Weight Gain (Twins) | Rate in 2nd & 3rd Trimester |
|---|---|---|---|---|
| Less than 18.5 | Underweight | 28-40 lbs (12.5-18 kg) | No guideline established | 1 lb (0.5 kg) per week |
| 18.5-24.9 | Normal Weight | 25-35 lbs (11.5-16 kg) | 37-54 lbs (17-25 kg) | 1 lb (0.5 kg) per week |
| 25.0-29.9 | Overweight | 15-25 lbs (7-11.5 kg) | 31-50 lbs (14-23 kg) | 0.6 lb (0.3 kg) per week |
| 30.0 and above | Obese | 11-20 lbs (5-9 kg) | 25-42 lbs (11-19 kg) | 0.5 lb (0.2 kg) per week |
First Trimester (Weeks 1-12): Minimal weight gain is expected, typically 1-4 pounds total. Some women may lose weight due to morning sickness, which is usually not concerning if weight gain catches up in the second trimester.
Second Trimester (Weeks 13-26): Steady weight gain begins, approximately 1 pound per week for normal-weight women. This is when most of the total pregnancy weight gain occurs.
Third Trimester (Weeks 27-40): Continued steady weight gain at the same rate as the second trimester. Some women may gain less in the final weeks as space for the baby becomes limited.
Gaining too little weight during pregnancy can lead to:
• Low birth weight baby (less than 5.5 pounds)
• Preterm birth
• Increased risk of infant mortality
• Developmental delays
• Difficulty breastfeeding due to inadequate energy stores
Gaining too much weight during pregnancy can lead to:
• Gestational diabetes
• High blood pressure and preeclampsia
• Complications during delivery
• Large-for-gestational-age baby (macrosomia)
• Increased risk of C-section
• Difficulty losing weight postpartum
• Increased risk of obesity later in life for both mother and child
Twin Pregnancies: Women carrying twins need to gain more weight than those with singleton pregnancies. The IOM provides specific guidelines for twin pregnancies based on pre-pregnancy BMI.
Adolescent Mothers: Teenage mothers who are still growing themselves may need to gain weight at the upper end of the recommended range or even more.
Women with Eating Disorders: Require specialized care and monitoring to ensure adequate nutrition and appropriate weight gain.
Short Intervals Between Pregnancies: Women who become pregnant within 18 months of a previous birth may need additional nutritional support.
Regular Exercise: With your doctor's approval, maintain regular physical activity. Walking, swimming, and prenatal yoga can help manage weight gain and improve overall health.
Frequent Monitoring: Track your weight gain regularly and discuss any concerns with your healthcare provider. They can help adjust recommendations based on your individual circumstances.
Hydration: Drink plenty of water and limit high-calorie beverages. Proper hydration supports healthy circulation and can help manage swelling.
Portion Control: Use smaller plates, eat slowly, and pay attention to hunger and fullness cues. Quality of food is more important than quantity.
Contact your healthcare provider if you experience:
• Sudden weight gain (more than 2-3 pounds in a week)
• Inability to gain weight after the first trimester
• Excessive weight gain despite healthy eating
• Signs of preeclampsia (swelling, headaches, vision changes)
• Persistent vomiting preventing weight gain