It is so much fun tracking the growth and changes in your baby. Your 16-week-old fetus is about 3 1/2 ounces and approximately 4 1/2 inches long. Your baby is really going to change fast; right now your baby’s skin is still transparent. Your baby’s legs are arms have developed greatly he or she has fingers and toes. Your baby’s ears are close to the position where they are going to be and the eyes are more on the front of its head.