Katherine Catone: many years ago (early 1980's) I heard a tape of Kittie's
saying that she believed but could not prove that there were multiple
let-downs in any breastfeeding episode. I wrote to her then, sending
photocopies of the relevant pages of a very special book. British
paediatrician Mavis Gunther had not only understood but clearly described
and documented how babies breastfeed as long ago as the 1950's,she had also
measured with a flow-meter, described and graphed the multiple rushes of
milk that some of us refer to as let-downs and others as MER's (neither
being very precise use of the English language, alas.) If you ever see an
old book called Infant Feeding (1970; Penguin 1975) be sure to read it and
wonder how the obvious could have been overlooked for so long. Mavis is the
lady who saved my sanity (and my kids' health) after three months of
excruciating nipple pain; Breastfeeding Matters owes its origins to her and
she is generously quoted therein. (Her work on nipple pain is still
unparalleled.) I find it hard to believe that not everyone believes in
multiple flows: just watch the rhythm of breastfeeding, which is triggered
by changes in volume delivered.

As for why they thought babies only needed to feed for a brief period: the
bulk of the milk by volume was ingested in that time and no-one appreciated
the importance to some babies of the small volume but fat-rich milk
ingested as the breast emptied.