Pregnancy weight gain is healthy because the baby, the uterus, the placenta, the amniotic fluid need to grow. Your baby's growth and development depend on you gaining adequate weight. Below are pregnancy weight gain guidelines established by reputable organizations. Not every gains exactly the same amount and how much weight gain you need depends on various factors, including your pre-pregnancy weight and body mass index (BMI). Your health and your baby's health also play a role. Work with your doctor to determine what's right for you. Pre-pregnancy weight and Recommended weight gain Underweight (BMI less than 18.5): 28 to 40 pounds (about 13 to 18 kilograms) Normal weight (BMI 18.5 to 24.9): 25 to 35 pounds (about 11 to 16 kilograms) Overweight (BMI 25 to 29.9): 15 to 25 pounds (about 7 to 11 kilograms) Obese (BMI 30 or more): 11 to 20 pounds (about 5 to 9 kilograms) The calculator below will show you exactly the range of healthy weight gain based on your BMI.