And the purpose of the milk is to basically provide that child with the nourishment that the child needs to basically grow and develop into a fully functional individual and the milk is also used to boost to increase the immunity of that child as we'll see in just a moment. So during the process of pregnancy when that woman is carrying that fetus and the fetus is undergoing different types of developmental processes, that woman is actually releasing estrogen as well as progesterone. So initially these two hormones are released by the corpus luteum found in the ovary but eventually the placenta takes over this job and begins to release estrogen and progesterone. And what these two hormones do is they stimulate the lobules of granular tissue and the ducts to actually increase in size and this ultimately increases the size of the breast themselves. Now, for a few days following childbirth the breasts will produce a fluid known as cholesterol. Now, cholesterol is also known as first milk and cholesterol is a yellowish substance that is rich in protein and lactose but has a relatively low concentration of fat and this is usually produced before childbirth and following childbirth.