12th April 2024

Oxytocin

Oxytocin has two main sites of action: the uterus and the mammary gland.(1) Oxytocin stimulates the myoepithelial layer in the uterus to contract to facilitate delivery. This sends neural signals to the brain to enhance oxytocin secretion, this positive feedback is broken once the baby is delivered. Increased amounts of maternal oxytocin are released in the third stage of labour (after delivery) as it has a role in stopping bleeding after labour, facilitating uterine involution and infant bonding. Positive feedback regulates the release of oxytocin in breastfeeding, suckling the nipple stimulates the paraventricular nucleus in the hypothalamus to produce more oxytocin. This leads to contractions of the myoepithelial cells surrounding the alveoli and ducts in the mammary glands to expel milk, triggering the ‘let down reflex.’.