Establishing a milk supply is a biological transition from a hormonally controlled system to a localized, demand-driven one. Before establishment, production is primarily governed by systemic hormones circulating in the bloodstream. Once established, the output becomes consistent and predictable, responding directly to the efficiency and frequency of milk removal. Understanding this progression helps parents set realistic expectations for the first weeks of the feeding journey.
The Initial Stages of Milk Production
Milk production, or lactogenesis, begins long before a baby is born, around the middle of pregnancy. During this initial stage, known as Lactogenesis I, the mammary secretory cells differentiate and begin producing colostrum, the nutrient-dense first milk. High levels of the hormone progesterone, produced by the placenta, suppress the volume of milk production, keeping the output low during this phase.
The second stage, Lactogenesis II, is triggered by a dramatic hormonal shift immediately following birth. When the placenta is delivered, there is a rapid drop in progesterone and estrogen, which removes the inhibitory brake on milk synthesis. With prolactin levels remaining high, this signal initiates the onset of copious milk secretion, often referred to as the milk “coming in.” This rapid increase in volume typically occurs between 30 and 72 hours postpartum, with many parents noticing a distinct feeling of fullness in their breasts by two to five days after delivery.
Frequent and effective milk removal in this window is important for preparing the breast tissue for the long-term maintenance of supply. Early stimulation ensures that the milk-producing cells, called lactocytes, are primed to respond to future demand. The supply during these first few days is primarily under endocrine control, meaning it happens regardless of whether the parent is feeding the baby.
When Supply Stabilization Occurs
The point when a milk supply is considered established marks the shift from endocrine (hormonal) control to autocrine (local) control, known as Lactogenesis III. This stabilization typically happens around four to six weeks postpartum, though the exact timeline can vary for each individual. After this transition, the amount of milk produced is largely determined by the frequency and thoroughness of milk removal from the breast.
The primary regulator of this autocrine system is a whey protein called Feedback Inhibitor of Lactation (FIL), which is present in the milk. If the breast remains full for extended periods, the concentration of FIL rises, signaling the lactocytes to slow down milk synthesis. Conversely, when the breast is thoroughly emptied, the FIL concentration drops, and the cells are signaled to accelerate production.
Parents often notice a change in the physical sensation of their breasts when stabilization occurs. The feeling of extreme engorgement, heaviness, or random leaking that was common in the first few weeks tends to diminish. Breasts may feel softer and less full before a feeding, which can sometimes lead to the mistaken belief that the supply has decreased. This softer texture simply reflects the body’s efficiency in matching production to the infant’s demand, maintaining a more consistent output rather than an oversupply.
Critical Practices for Maintaining Supply
Maintaining an established milk supply relies heavily on the principle of supply and demand, where milk removal drives milk creation. To protect the supply, frequent and effective milk removal remains the single most important factor. This typically means nursing or pumping at least eight to twelve times in a 24-hour period, especially in the early months.
Monitoring the infant’s signs of adequate intake is the most reliable way to confirm the supply is being maintained. This involves tracking appropriate weight gain and consistent output of wet and dirty diapers. If the infant is thriving, it indicates the supply is meeting their needs, regardless of the parent’s breast sensation or pump output.
Protecting the established supply involves avoiding long, unscheduled gaps between milk removal sessions. Addressing issues like a poor latch or incorrect flange size for pumping is also important, as inefficient milk removal can quickly lead to a gradual decrease in production.