>Hello wise ones, can you please help me out of a confusion in my bf-theory
>education?  I seem to have learned two things that seem to be contradictory,
>but I suspect I am just missing third, explanatory fact that will clarify all.
>
>On the one hand I was taught that the foremilk is present in the breast before
>the baby begins to feed, and that the continued suction causes the breast
>actually to produce the hindmilk as the feed continues.
>
>On the other hand I have heard from many of you that breast compression
>increases the calories that a baby is getting during the feeding.
>
>I used to believe that this was because it stimulated the breasts to better
>let down, or drain out, hindmilk that was already in the breasts, high and
>back in the milk sinuses.  But this seems would suggest that the hindmilk was
>in fact already in the breast at that time, and seems inconsistent with the
>idea that the hindmilk is actually produced while the baby in nursing.
>
>So then does breast compression somehow send a signal to the breasts to
>produce a higher proportion of hindmilk than they are stimulated to do by
>suckling alone?  And if so, is anything known of the mechanism through which
>this works?
>
>Any clarification from those with better lactational anatomy than mine will be
>much appreciated.

Hi Elisheva,
Perhaps a few facts might help here:
1. Milk is being produced at all times during a lactation, but the rate of
synthesis varies.
2. Between feeds, some low-fat milk ('foremilk') gradually moves down to
fill the sinuses.
2. The 'emptier' the breast, the faster the rate of milk synthesis in the
alveoli. (Controlled by autocrine control - with an inhibitor in the milk
itself.)
3. Fat globules, when added to the milk during synthesis, adhere to the
walls of the alveoli, high up in the breast, near the site of synthesis.
4. When the let-down reflex is triggered, oxytocin causes the muscle cells
surrounding the alveoli to contract and 'squeeze' the milk down the ducts
so it becomes available to the baby to milk out. As the alveoli start to
empty, the fat globules start becoming dislodged and move down the ducts.
So the further into the feed, the higher the fat content of the milk coming
out the nipple, as more and more fat globules are forced off the alveoli
walls.
(I would presume that breast compression would help hasten the dislogement
of the fat globules and therefore increase the fat content, but this is
only my theory.)
5. There is no sharp distinction between foremilk and hindmilk - it is a
gradual change from the moment of the let-down  (the first pulse of
oxytocin, and there are several per feed, although most mothers only notice
the first one) when the milk in the alveoli starts being squeezed out and
into the ducts.

I have gleaned this information over the years from listening to numerous
presentations by Peter Hartmann and his students. Some of their papers
describe much of this.

Another interesting fact is that, in the normal mother with a healthy,
exclusively breastfed singleton baby, milk supply is surprisingly constant,
at least between one and six months. In a study Peter and his students did
to look at the levels of prolactin in relation to milk supply, they found
that prolactin levels drop over time but milk supply remains constant.
First revelation was that prolactin is not determining the rate of milk
synthesis after the initial period of lactation (but we already knew it was
controlled by the autocrine system by one month), and second revelation, to
my surprise at the time, was that appetite increases (ie 'growth spurts'),
did not result in a persisting higher milk production in the mother. My
only explanation for extra-frequent feeding periods is that baby
*temporarily* needs more, but returns to the original amount after the
'growth spurt' appears to have passed. A bit like a teenager suddenly
eating everything in the house, and when you stock up big to compensate, he
suddenly goes back to what he used to eat, and you're left with a
cupboard-full of food! (We have actually 'talked' about this before on
Lactnet, so if you want more, you could search the archives.)

This is not to say that a mother cannot increase her supply by frequent
feeding. If it goes on long enough, it will increase the amount of milk
synthesised, as the autocrine control will ensure high synthesis rates
whenever the breasts are relatively empty (which would be most of the
time!). In fact, I think I recall Peter saying that with *really* prolonged
increased demand (like in an adoptive situation, eg), you actually can get
increased division of the cells to make more milk sythesising tissue in the
breast.

Fascinating stuff, eh?

******************************************************************
Joy Anderson B.Sc. Dip.Ed. Grad.Dip.Med.Tech. IBCLC
Nursing Mothers' Association of Australia Breastfeeding Counsellor
Perth, Western Australia.   mailto:[log in to unmask]
******************************************************************