Re the idea of explaining how a breast is never really empty: I thought the
analogy of a sink with tap [faucet, for you foreigners ;-) ] running was
great. I think it could also be useful for explaining the concept of
autocrine control of milk production. ie The rate at which the tap is
running (milk production rate) changes with the level of water in the sink
(relative fullness of the breast). When the sink is full to overflowing,
the tap drips slowly, but when the water is let out completely the tap runs
in a moderate stream. If the water is partially let out, the water flow
from the tap is in between. I like to explain to mothers that just when
they feel their breasts are empty after frequent feeding of an unsettled
baby, that this is the time they are making milk at maximum rate. So if
they wait just a little while (say 20 minutes) they will have more for
their baby.

I'm not sure if all of you are familiar with the concept of autocrine
control of breastmilk production. As Fiona Coombes put in a post the other
day, we are fortunate to have Peter Hartmann in Western Australia who does
really interesting research into lactation. He keeps us up-to-date with
this sort of stuff. Briefly, the autocrine system explains "supply and
demand" and how each breast can be independent in its supply. This system
kicks in as the major supply controller after the initial endocrine control
(via prolactin) of the early days. An inhibitor is produced in the milk,
which when it accumulates (breast left full) inhibits the milk production
and slows the rate. When the breast is "emptied", the inhibitor is removed
and milk production rate rises. After each feed the milk production rate in
each breast is determined by the amount of milk left behind by the baby. As
you all probably know, the amount of milk taken by the baby is determined
by his appetite, and not by how much is available in the breast, so
variable amounts get left over after feeds at different times. Therefore,
milk production rate is constantly changing and adapting to the baby's
need. I find the way nature has designed this system to be incredibly
fascinating. The more I learn about this, the more mind-blowing it becomes.
Hope you all find this as interesting as I do.

Joy Anderson
Western Australia