How much weight you can expect to put on during the course of your pregnancy depends on what weight you are at the start of your pregnancy.
On average, a healthy, average-sized woman who eats normally in pregnancy can expect to gain between 11-13 kilo's. As a guide 0-3 kilo's in the first trimester and roughly about ½ a kilo a week from then on. But don't worry too much about the weight you will gain, the important thing is you eat well. Pregnancy is not a time for dieting, your baby needs to be well nourished.