Women who are at a healthy weight when they become pregnant shouldn't expect to gain much in the first trimester -- only about 1 to 4 pounds (0.4 to 1.8 kilograms). The rest of the pregnancy averages about a pound of weight per week, totaling about 25 to 35 pounds (11 to 16 kilograms). Women who are overweight or obese may be advised to gain less, and vice versa for women who begin pregnancy underweight. If you're expecting multiples, expect a greater weight gain. Your doctor will council you on reasonable weight goals during your first visit.
Where does it all go? It may feel as if your pregnancy weight gain is all in your belly, breasts and thighs, but a woman's weight gain is distributed among her breasts, uterus, blood, fat, muscle, placenta and amniotic fluid -- plus the baby. And no, it's not your imagination: You're retaining about 4 pounds (1.8 kilograms) of water.