Weight gain during pregnancy starts around the third month due to an  increase in the size of various organs, like the uterus and the breasts.  The total weight gain differs from woman to woman, but should not be  more than about 10-12 kgs.

The  first thing to do is to see that you are eating the foods which are  part of a well-balanced diet. The "eating for two" concept is outdated.  What is important is that you get adequate nourishment in the form of  vitamins, proteins and minerals for your own and your baby's well being.  Your doctor will prescribe vitamins, calcium and iron supplements to  check deficiencies and the baby will help himself according to his  requirements.