Lactation is the biological process through which a mother produces and releases breast milk to nourish her infant. This process is primarily regulated by hormones, with prolactin stimulating milk production and oxytocin triggering milk release, often referred to as the letdown response. The act of suckling by the infant plays a crucial role in this hormonal regulation. When the baby suckles, sensory nerves send signals to the mother's hypothalamus, a key brain region that controls hormonal activity. The hypothalamus then signals the pituitary gland to secrete prolactin and oxytocin, facilitating milk synthesis and ejection respectively.
In the initial days after birth, the mother produces colostrum, a thick, yellowish first milk rich in micronutrients and antibodies that provide essential immune protection to the newborn. This early milk is distinct from mature breast milk, which develops fully around four to six days postpartum and contains a balanced composition of nutrients necessary to support the infant’s growth for the first six months.
During each breastfeeding session, breast milk composition dynamically changes from foremilk to hindmilk. Foremilk is more watery with lower fat content, designed to quench the baby’s thirst. As feeding continues, the milk transitions to hindmilk, which is thicker and richer in fat, providing the energy required for the infant’s development and satiety. This adaptive quality of breast milk ensures that the infant receives both hydration and nourishment in appropriate proportions throughout feeding.
Understanding the hormonal control of lactation and the nutritional evolution of breast milk highlights the intricate biological mechanisms that support infant health and development during breastfeeding.
