There is no such thing as the best amount of weight to gain during pregnancy; the appropriate pregnancy weight should be estimated based on each individual’s pre-pregnancy weight. At different stages of pregnancy, a pregnant woman’s weight needs to be based on her pre-pregnancy body mass index (BMI) to determine whether her weight gain during pregnancy is reasonable or not. The BMI is calculated by dividing her weight in kilograms by the square of her height. Pregnant women with a pre-pregnancy BMI of less than 18.5, i.e. underweight, should have a reasonable weight gain range of 25 to 36 pounds during pregnancy. Pregnant women with a pre-pregnancy BMI between 18.5 and 24.9, i.e. normal weight, should have a weight gain of 23 to 32 pounds during pregnancy. Pregnant women whose pre-pregnancy BMI is between 25 and 29.9 should have a weight gain of 14 to 23 pounds. A pre-pregnancy body mass index greater than 30, weight gain should be in the range of 10 to 18 pounds. Reasonable control of weight during pregnancy will help the health of the fetus and the smooth delivery of the pregnant woman. Pregnant women should undergo regular labor and delivery checkups and seek prompt medical attention when discomfort occurs.