typically, if your in the normal weight range, you need to gain between 20-25 pounds. More or less depending on current weight factors. After the baby is born, the best way to prevent extra weight is to eat plenty of fruits and vegetables. Doesn't mean to go all out and diet. Just eat better and lay off the soda's and tea's (at least the super sugary ones). Having a baby will put a small damper on the exercise after they are born but don't lie around the house all the time. Those things help a lot. I went down to my pre-pregnancy weight but now I've gained the weight back due to Thanksgiving! And now I'm pregnant again... so I've got no choice but to gain around 15-20 pounds. I'm over my weight range.