Expected weight gain during pregnancy varies from woman-to-woman and depends on several factors (body type, weight prior to pregnancy, eating habits, etc). The average weight gain for most women is somewhere between 25 to 35 pounds.

According to the American College of Obstetricians and Gynecologists, the average weight during pregnancy can be broken down as follows:

Baby 7.5 pounds
Maternal energy stores (fat, protein, and other nutrients) 7 pounds
Fluid volume 4 pounds
Breast enlargement 2 pounds
Uterus 2 pounds
Amniotic fluid 2 pounds
Placenta 1.5 pounds

Average weight gain per trimester:

First trimester 3 to 4 pounds
Second trimester 12 to 14 pounds
Third trimester 8 to 10 pounds
Weight Gain During Pregnancy