Physiology · Reproductive Physiology

Lactation and its hormonal regulation

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Definition

  • Lactation is the synthesis and secretion of milk from mammary alveoli, initiated after parturition when the high prolactin of pregnancy acts unopposed by falling estrogen and progesterone.
  • Colostrum, a protein-rich fluid secreted immediately after delivery, is replaced by mature milk in 24 to 48 hours.

Breast Milk: Composition and Functional Significance

  • Human milk supplies carbohydrate (lactose), protein (casein), fat, minerals and vitamins in adequate quantity, and contains antibodies protecting the newborn from infection.

Composition of human milk, major constituents

Component

Water

Amount
87%

Solids

Amount
13%

Protein

Amount
2.5 g%

Carbohydrate (lactose)

Amount
6 g%

Fat

Amount
5 g%

Calories

Amount
67 kcal/100 g