35 Weeks Pregnant What to Expect. Development and Changes. Week 35 - Day 1, You gain weight at a slightly faster rate. Week 35 - Day 2, Your baby is 35 Weeks Pregnant Pregnancy Body Changes at Thirty Five Weeks Pregnant. This week begins your baby's most rapid period of weight gain about 8 to 12 35th week of pregnancy, your baby is going to be concentrating on weight gain, to fill out his arms and legs into those plump little limbs we all know and ...