Library · Physiology
The milk letdown reflex
Make it clearer
Making milk and getting it out are two different things. Getting it out is a reflex, and what triggers it is a hormone, oxytocin. What it does is contract the myoepithelial cells, cells with muscle-like properties that wrap around the alveoli, the little sacs where milk is stored. When they contract, they push the milk toward the ducts.
Think of a tiny muscle hugging each milk sac and squeezing it.
That oxytocin is not made in the breast. It is made in the paraventricular nucleus of the hypothalamus, an area of the brain, and released from the posterior pituitary, the gland that hangs just below it.
It acts fast, and the baby does not have to be latched on: seeing, hearing, smelling or just thinking about the baby is enough. The same pathway cuts both ways: emotional stress can hold back the release of oxytocin and make it harder for the milk to come out.
In brief
Letdown is a reflex: oxytocin contracts the myoepithelial cells around the alveoli and pushes milk into the ducts.
A tiny muscle hugging each milk sac and squeezing it.
That oxytocin is made in the paraventricular nucleus of the hypothalamus and released from the posterior pituitary.
It acts fast, and suckling triggers it, but so does seeing, hearing, smelling or thinking about the baby.
Emotional stress can hold back that release and make milk harder to get out.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Breast Milk, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingOxytocin, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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