The amount of weight you should gain during pregnancy depends on your pre pregnancy BMI (Body Mass Index).
Women who are underweight before pregnancy should gain more weight than women who are heavier. If you are younger than 20 years old, your weight gain should be as close as possible to the maximum recommended weight gain. If you are pregnant with more than one baby your weight gain needs will increase.
To find out how much weight you should gain, use the following formula. You must know your height and weight before your pregnancy.