Breastmilk production – how breast milk is made
Your body begins the process of making breastmilk as soon as you become pregnant. There are many hormones involved in preparing your breasts to produce milk. During pregnancy hormones control milk supply, but once you give birth your milk supply is controlled by supply and demand. Hormones always control the process of producing milk, but your baby will tell your body exactly how much milk to make by how often she or he nurses. A full breast means slower milk production. An empty breast means faster milk production and higher fat content. The more your baby empties your breast, the more milk your body will make.
There are two different parts to making milk. The first is lactogenesis I which happens about halfway through pregnancy (each women and pregnancy is different). This is the process of producing colostrum. Lactogenesis II begins when the placenta is completely out of the uterus, which causes a huge drop in progesterone levels. Lactogenesis II is complete about 2-4 days after birth when a woman’s milk “comes in”. During lactogenesis II, you will experience a huge increase in milk volume. Your body is ready to make as much milk as your baby needs. After a few weeks of nursing your baby on cue your body will recognize how much milk it needs to make for this particular baby and you will find that your supply evens out.
There are two main hormones necessary for making and moving breastmilk. The first is prolactin. Prolactin causes breasts to produce milk. The second hormone is oxytocin. Oxytocin moves the milk and causes the “let down” reflex. This reflex may feel like a slight tingling or stinging in your breasts.