Sucking by infant initiates hormonal changes that lead to milk production and let down reflex, which releases milk.
The let-down reflex(Figure)
Suckling by the infant initiates hormonal changes that lead to milk production and the let-down reflex. This reflex releases the milk from storage cells in the breast.
The process of lactation is controlled by various hormones. The source of these hormones and their function is summarised in table.
Table: Hormonal control of lactation
Hormone
Source
Function
Estrogen
Ovary
Stimulates breast development during pregnancy.
Progesterone
Placenta
Stimulates milk production
Prolactin
Anterior pituitary gland
Stimulates milk production
Oxytocin
Posterior pituitary gland
In “let down” reflex: smooth muscles surrounding the alveoli of the nipples contract to allow the release of milk. In pain, emotions or embarrassment the let down reflex may sometimes be inhibited. Mother's doubt about ability to produce enough milk which can also interfere with the “let down” reflex.