Traditionally, in the immediate postpartum, language around “milk coming in” refers to the physiological process called lactogenesis II. Milk volume increases due to a hormonal response set off by frequent nipple stimulation and milk removal in the initial days after birth. The breast milk made in the first 3-4 days is called colostrum, and it completely supports your baby’s nutritional needs. Colostrum is even a laxative to help baby pass meconium! Many new parents do not acknowledge that colostrum is breast milk, but it is! However, some women experience a delay beyond this for a variety of medical reasons called delayed lactogenesis II. Your first step should be to contact an IBCLC for assessment. They will want to evaluate how your baby is latching, as well as how many wet and soiled diapers you’re getting in a day. They will also give you guidance on how to stimulate your milk-making cells and take a detailed history to identify the cause of the delay.