The Baby, 17 Weeks

Your baby weighs about 5 ounces now, and he's around 5 inches long — about the size of a large onion. My other book says he or she is about the size of my hand, outstretched. He can move his joints, and his skeleton — until now rubbery cartilage — is starting to harden to bone. His sense of hearing is also developing. The umbilical cord, his lifeline to the placenta, is growing stronger and thicker. Other stuff in my book... "Fat begins to form during this week and the weeks that follow. Also called the adipose tissue, fat is important to the body's heat production and metabolism. At 17 weeks, water makes up about 3 ounces of your baby's body. In a baby at term, fat makes up about 5 and one-fourth pounds of the total average weight of 7 and three-fourths pounds."