Final answer:
The watery, yellowish milk produced by the mammary glands in the first few days after childbirth is known as colostrum. It transitions to mature milk around day 10 postpartum, with foremilk being watery to quench thirst and hindmilk being creamier to satisfy hunger.
Step-by-step explanation:
In the initial days of lactation, the composition of breast milk undergoes significant changes. Colostrum, the first milk produced after childbirth, is a thick, yellowish fluid high in protein, vitamins, and immunoglobulins, providing the newborn with essential initial immunity. Colostrum also helps the newborn’s digestive system expel the first stool, known as meconium.
As lactation progresses, typically by the third postpartum day, the breast begins to secrete transitional milk, which is an intermediate stage between colostrum and mature milk. By approximately day 10 postpartum, mature milk is produced, which changes in composition from the beginning to the end of each feeding. The early milk or foremilk is watery and rich in lactose and protein, quenching the infant's thirst. The milk towards the end of the feeding, called hindmilk, is creamier and richer in fat, satisfying the infant’s hunger.
Apart from feeding, breastfeeding plays a role in the mother's health. The process of suckling stimulates oxytocin release, aiding in the involution of the uterus and promoting maternal bonding.