For the most part, breast milk is produced based on the actual needs of the baby, the more often and effectively the baby suckles, the more milk the mother's body produces. Milk will flow from the lobules into the collecting ducts in each lobe and then go to the milk sinuses under the areola. There are a total of 5-10 milk ducts that open at the nipple. The process of producing breast milk is affected by 4 hormones: estrogen, progesterone, prolactin and oxytocin.