Sometime ago, someone on LACTNET asked about the implications of the
article in Pediatrics (97:492-98, 1996) by Hamosh, etal re: the storage of
human milk. Briefly-for those who haven't read it yet-the article reported
on the results of storage of human milk (fresh, refrigerated) over time,
and bacterial growth and other changes that might have occurred in the
milk.

Hamosh and colleagues sought to answer two questions:  a) how stable are
milk nutrients over time? and b) What bacterial growth occurs without cold
storage?

They used two groups of women, those who expressed their milk at home and
those who did so in the hospital (usually because they had sick/premie
infants).

Key finding: Mothers who expressed in the home rather than the hospital
were very likely to obtain milk that was not contaminated by bacteria.
There was *almost no growth* in then first 24 hours if pumped and stored at
home at 15°C (refrigerated temp, I believe).

Bacteria were confined to staph epi in home expressed milk.  If the mothers
were expressing and storing in the hospital, a-strep and b-coliform was
found in the milk.

Proteins changed little with expression and storage, but fats concentrated
rapidly. The authors therefore suggested that storage should be for 4 hour
periods or less!

Personally, I question this, after having worked for many many years with
mothers who have stored milk for periods far longer than 4 hours.  

Note as well that this limitation is for milk that is stored at 38°C. 
Unless I am converting incorrectly, that is HIGHER than normal body
temperature! (Please correct me if I am wrong on this).  Most women do not
work in settings with a room temperature in the 90°s!  Milk that has been
expressed at body temp is not going to remain at that temperature if in a
container in a room that is not that warm.  If placed on ice, that too is
going to reduce the temperature of the milk, as would refrigeration or
freezing.

I consider this study to be helpful insofar as it notes minimal protein
changes and the differences in "cleanliness" of the milk when expressed at
home as opposed to a hopsital, but it does not answer those same questions
for work sites other than a hospital NICU, nor does it acknowledge that
most women do not operate in a room temperature lower than body
temperature.  We still need to determine how fats change in settings other
than the breast.

Anyone planning a study in an effort to answer these questions needs to
attempt to replicate "typical" work settings that women inhabit for several
hours a day.
Consider this a hint!

       

 
Def. of LC service: "We are all faced with a series of great opportunities
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Kathleen G. Auerbach,PhD, IBCLC (Homewood, IL)- [log in to unmask]
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