Monster Update: 16

At 4 1/2 inches long (head to bottom) and 3 1/2 ounces, the Tummy Monster is about the size of an avocado (pictured). In the next three weeks, it'll go through a tremendous growth spurt, though, doubling its weight and adding inches. The Monster's lower limbs are much more developed now. Its head is more erect than it has been, and its eyes have moved toward the front of the head. Also, the Monster's ears are close to their final position, too. Some of its more advanced body systems are working, including the circulatory system and urinary tract. The Monster's heart is now pumping about 25 quarts of blood each day, circulating its total blood volume through her body many times. (By the end of Stef's pregnancy, this will increase to about 190 quarts.) The patterning of its scalp has begun, though no hair isn't recognizable yet. Although closed, the Monster's eyes are moving (slowly). Plus? The Monster has started growing toenails.

Text adapted from Baby Center.