Between now and delivery, your baby will gain more than half of its birth weight. Now that you're 33 weeks pregnant, your baby may have a full 33 Weeks Pregnant. Pregnancy Body Changes. By week 33 of pregnancy, about half a pound a week of your weight gain is going to your baby. You may be weight gain shows in the size of your belly when you're 33 Weeks pregnant! The shape of your belly changes as the belly drops due to the baby turning in a ...