Week 33 and webmd.com says, "Your baby measures about 19.4 inches from head to toe and weighs about 4.4 pounds. The next few weeks will mark lots of growth in the baby. The fetus will gain more than half its birth weight in the next seven weeks. Baby begins to move less now as it runs out of room and curls up with knees bent, chin resting on chest and arms and legs crossed." Wow, could you imagine growing half an inch in one week?! That's some serious length gain.