Weight Gain During Pregnancy Body type | Acceptable Gain | Underweight | 28 to 40 lbs | Normal Weight | 25 to 35 lbs | Overweight | 15 to 25 lbs | How Weight is Distributed | from: A.C.O.G | 7 lbs | Maternal stores (fat, protein, and other nutrients) | 4 lbs | Increased fluid volume | 2 lbs | Breast enlargement | 2 lbs | uterus | 7 1/2 lbs | Baby | 2 lbs | amniotic fluid | 1 1/2 lbs | Placenta (afterbirth) | |