During which stage does lactogenesis begin to occur?

Lactogenesis, the process of milk production, is fundamentally tied to the hormonal changes that occur during pregnancy. It is subdivided into three distinct stages:

Stage I corresponds to mid-pregnancy and is characterized by the preparation of the mammary glands for lactation. In this stage, the alveolar cells of the breast begin to proliferate and differentiate in response to hormonal influences, primarily from estrogen and progesterone. The structural and functional changes that occur during this stage are crucial as they set the groundwork for subsequent milk production.

Stage II, which occurs immediately postpartum, represents the onset of copious milk production, facilitated by the abrupt drop in estrogen and progesterone levels after delivery and the stimulation from suckling. During this time, mature milk is synthesized and released, marking the transition to full lactation.

Stage III, late pregnancy, does not encapsulate the onset of milk production, as the changes leading to actual secretion do not happen until after birth.

Stage IV, post-lactation, signifies a period where lactogenesis ceases, and milk production decreases or stops altogether.

Thus, lactogenesis begins in Stage I during mid-pregnancy, aligning with the biological preparatory changes within the breast tissue, which are essential for successful