Copious milk production, which usually occurs by the fifth day after the birth, can't always be measured by a feeling of fullness in the breasts. This is because if your baby is feeding frequently and flexibly, you mightn't experience breast fullness when your milk comes in.

Fullness of the breasts might also signal that you've had an overshoot in milk production beyond what your baby needs, and the fullness is in fact dialing down or calibrating your supply.

But if you're not offering your breast often enough to your baby, the supply may dial down too much and then not meet your baby’s needs.

If you don’t have copious milk production by the end of day five, measured by baby’s throughput and baby beginning to gain weight well, we refer to this as delayed secretory activation. There are a number of causes for this, that your health professionals will screen for. You can find a list of possible causes here.