When a baby suckles at its mother's breast the stimulus at the breast is sent to the mother's brain (a region called the hypothalamus). the brain responds by releasing hormones to stimulate the production and the ejection of milk from the breast. this the newborn to receive nourishment and encourages more suckling. this example is best described as a

Yikes.

This is known as positive feedback. It is a continuous loop, that occurs when something physiological is altered.

When this alteration changes, an even stronger change is made in that equivalent direction. 

What I mean by this, is that the physiological change of the baby interacting with the mother caused an increase in that same direction. 

The increase in that same direction is the production of hormones, which raised the amount of milk.

Hopefully, this helps!