During the third month of your pregnancy, your baby's bones begin to ossify or harden. Your baby is already moving spontaneously, but you usually can't feel these movements for awhile yet. Your baby's eyes are large and open. Eyelids will form later. External ears have formed. External genitalia begin to differentiate, though it's still very difficult to tell whether your baby is a girl or a boy without genetic screening. Your baby moves from being an embryo to the foetal period, now called a foetus. S/he also loses their tail! Your baby's head is the biggest part of their body. It is about 1/2 the size of the rest of the body. While the head is large, the brain's structure is similar to what it will be at birth. S/he weighs about 14 grams and is approximately 3.54 inches in total length. By the end of this month you should be able to hear your baby's heart beat with a Doppler.