Supply and Flow: How they're related and how they matter to baby!

Understanding breastfeeding and how babies respond starts with understanding that their is a difference between supply and flow.  The are certainly related, and they function with each other, but they aren't the same thing.

Supply

Pretty self explanatory.  Your supply is how much milk you have.  The quantity of milk available to your baby.  Your supply can change over the course of your breastfeeding relationship, and it needs to be well established pretty early on.
People talk a lot about supply.  They talk about over supply, and undersupply and often post pictures of freezers full of pumped milk with comments about how grateful they are for such a wonderful supply.

The thing is, how much milk is available to baby, doesn't actually dictate how much they get.  

Think of your supply as the amount of water available in this water tower.  There might be lots of water available and there might be very little, but up there in the tower it isn't accessible to anyone.  In order for your family to have access to the water, the tap needs to be hooked up properly and turned on.  If there is a problem with the plumbing, or the tap is only turned on a little, drinking water from that tap will be frustrating!

Flow

The flow is the speed that the milk comes out of the breast.  Flow changes over the course of the day and over the course of the breastfeeding relationship.  Babies can be VERY sensitive to flow.  They complain when it's to slow and complain when it's faster then they can handle.  And even though they can't talk, they will tell you when something is wrong with it. 
  

When your baby is latched on well, they can handle the flow that comes out of the breast.  They drink until the flow slows down and then they use their tongue and the latch to help trigger more milk.  
When the flow slows down, they tell you, either by falling asleep, or by just looking less satisfied at the breast.  They wiggle, pull and tug at the nipple, squirm, punch or pinch at the breast and sometimes bite to try and increase the flow.
If you do something to increase the flow (add a compression to make the space where the milk lives smaller, or switch sides) or do something to distract them from the slower flow (bum pats, bouncing, walking around) you can sometimes convince them to stay at the breast until it speeds up again.  

Because flow and supply are related (more supply usually means faster flow), the answer to slowed flow is often to increase supply.  

Babies are sensitive to flow - some more then others!  If the flow changes babies often respond with a change in their behavior.  Sometimes those changes make sense and sometimes it takes someone else to help you see what's going on, but if your baby isn't as happy as they were, consider the flow.  It could be part of the problem!