If you don't gain enough weight, your baby may weigh too little. The current recommendation for most women is to gain 25 to 35 pounds during pregnancy. Teens or underweight women may need to gain 28 to 40 pounds. Overweight women may be advised to gain only 15 to 25 pounds. The target weight for a woman carrying twins is 35 to 45 pounds.
Body weight increases at different rates during pregnancy.
In the first trimester, weight gain is slow at only two to four pounds. During the last six months, you will gain about one pound per week. It's important that your weight increase steadily. You should report any sudden weight changes to your healthcare provider. You will lose about 12 to 14 pounds within a week after childbirth.