Dear all:

First, I want to make it very clear that I think the work done on the WHO charts is excellent and 
that one does have to make clearcut decisions about which infants to include.  You cannot include 
the entire population.  I was working on my doctorate during some of the early debates about how 
to select the population for study and the fine nuances between "healthy" and "normal" were hotly 
debated.  It is extremely difficult to get a large enough sample with enough date points to 
construct these curves.  So, my comments on interpretation of these charts for individual infants 
does not detract from how important I think these new charts are for public health purposes.

Also, I must spend too much time on subways where my brain races into high gear with nothing to 
occupy it.  So, in one of those long subway rides I started to rethink my interpretation of  Kathy 
Dettwyler's prior comments on the potential influence of sleep trained babies on the high end of 
the spectrum. because of a recent talk by Thomas Hale.

Thomas Hale presented some (I think) unpublished data from Australia on rates of milk synthesis 
being constant throughout the day and unrelated to prolactin levels once prolactin is above a 
certain baseline level.  Mothers pumped 1x/hour.  I can't remember if they did this for a full 24 
hours or maybe a more kindly 12 hours.  Once the backlog of stored milk was cleared the rate of 
synthesis was constant at an average rate of about 32 to 37 ml/hour.  Time of day did not matter. 
The conclusion was that milk synthesis is a constant and that variations in intake of infants is 
merely due to the fact that they eat at different rates and frequencies so that the amount stored 
between feedings varies.  The larger volumes typically seen in the morning is merely due to the 
fact that infants typically go slightly longer between feeds at night.  And if I got his gist properly, 
others who have a larger milk storage capacity are able to store milk for longer periods without 
experiencing the cell die-off that would reduce their production capacity than women with a lower 
milk storage capacity.

So, between that study and the two studies showing the milk volume, not milk composition 
influences the rate of growth, I'm beginning to think that the feeding routine of Davis moms may 
be irrelevant.  What this study suggests to me is that infants that might grow at a slower rate 
because of a feeding routine that stretched out their feedings to a lower frequeny than they 
needed would be among infants who had mothers with a lower storage capacity.  These women 
would be the ones who would experience a reduction in milk supply from not draining their 
breast,  Had these mothers fed their infants as frequently as they wanted, they may not have been 
the infants that gained at the top of the range of growth anyway because the storage capacity was 
limited.  So, any influence of stretching out feedings would have caused shifts in the middle or 
lower end of the spectrum, not the high end.  The frequency of feeding infants would have far less 
impact in women with a larger milk storage capacity who might have the capacity to feed the 
infants at the top end of the spectrum.  From this latest research it seems to me that it doesn't 
matter - they will produce milk at a copious rate anyway as long as their infants are being fed 
within a reasonable range of frequency --- and I'm sure that the study design ensured that these 
infants were not being fed on some of the extreme routines I ocaissionally encounter such as the 
three month olds who are being fed four times a day because some mom read a book that told her 
to do it or because she eats three times a day she thinks her baby should eat at the same rate.

Best regards, Susan Burger  

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