My geuss would be that the amount of weight that you are meant to put on is between 5kg and 50kg . There are so many variables - the build and height of the woman, whether she is underweight or overweight at the beginning of the pregnancy, fluid retention, quitting smoking (you put on more weight but its so much healthier) etc etc. I think that to say there is an ideal amount of wieght is just putting an extra little stress on women at a time that we really don't need it. What is more important is wether we are eating well and getting the right amount of excercise. If you are worried you could discuss it with your care provider and they should be able to tell you without the aid of scales if your weight gain is healthy. AFAIK most women lose thier baby fat relativley easily.