Your baby’s ears protrude from a tiny head as inner ear bones (as well as leg bones) begin to solidify. The skeleton will keep ossifying. Your baby will hear and acknowledge the raucous environment of your uterus, your tummy echoing, blood whizzing through your vessels and the rhythm of your heart beating. Your baby will also become aware of loud noises outside the womb. In this eighteenth week of your gestational journey, your baby is roughly 5½ inches in length, 7 ounces in weight and about the size of a delicious naval orange.