the process requires first stimulation of the
breast tissue by the hormones of pregnancy (
estrogen, progesterone, human placental lactogen), as well as your own hormones (prolactin, thyroid, insulin), and second the hormones of pregnancy must fall rapidly, as occurs after the placenta separates at birth. at this point the breasts become tremendously engorged, and then they start to release milk when they are stimulated and/or when you see, hear or smell your baby.