Dear Friends,
On Jan 22, Mandy O'Reilly said "I have had a inquiry from a PhD student who
wants to know if there is a formula for estimating breastmilk volume (intake)
based on the number of feeds per 24 hrs and the duration of the feed. I am
not aware of one myself and can't see how one could measure it short of 24 hr
test weighing. Any ideas?"

On Jan 26, Marie Davis asked "there is something that has always bothered me
about pre and post weights. Has anyone ever documented that one fluid cc of
BREASTMILK is equal to one gram of weight?"

I remember reading an article about this, in which the researcher admitted
that milk was just a tad heavier than water, but had done the calculation
showing that this difference compensated for the tiny loss of weight a baby
experiences through insensible water loss between the beginning and the end
of a feed.  The upshot was that test weighing does give us a close enough
estimate of the baby's milk intake.

Kathy Rubin's points about spilled milk and test weights are excellent, and
we have to remember that milk can end up on the shirts of nursing babies as
well as bottle fed babies.

Peter Hartman and his colleagues have shown that test weighing is just as
accurate when one weighs the mother before and after feeds, as when one
weighs the baby, provided one does a calculation to offset the mother's
insensible water loss.  And Mike Woolridge and colleagues in Thailand found
that weighing the mother at bedtime and first thing in the morning was a good
enough method for estimating the milk intake of babies who slept and smooched
at the breast all night----provided that the mother didn't eat, drink, or use
the toilet between the two weighings.

I would give Mandy's PhD student this article (which I discuss every time I
teach A&P of breastfeeding):  Woolridge MW, JD Baum, RF Drewett (1982).
Individual patterns of milk intake during breast feeding. Early Human
Development 7, 265-272.  This is the study in which a group of 20 6-day-old
babies were test-weighed and timed while feeding.  The one baby who nursed
the shortest time (4 minutes on one breast) took the same amount of milk as
the average intake of the eight babies who nursed the longest (an average
total of 22 minutes on both breasts).  I love to go carefully through the
graph that shows how long the babies fed and how much they took in, and then
ask the students to show me the relationship of the length of feeding to the
amount taken.  Essentially, there is none!

During this thread, several people have commented on variations in fat
content.  I think this is another one of Mother Nature's little traps for
people who want to know too much.  Babies can take in greater or lesser
quantities of higher-calorie milk or lower-calorie milk.  So even when you
get the volume by test weighing, you don't know much if you don't know how
creamy the milk was and the beginning and the end of the feed.  Another
article I always use when I teach is: Woolridge MW and JD Baum (1991). Infant
appetite control and the regulation of breast milk supply. Children's
Hospital Quarterly 3:2, 113-119.  This one demonstrates the tremendous
differences in milk fat content there can be from one woman to another, and
even, for some women, between feeding on one breast per feed or on both
breasts per feed.  Again, unless we are doing detailed assessments in a lab
situation, we are quite unable to guess how many calories a baby is taking
in, even if we know the amount of milk the baby takes.  And, guess what?  We
don't HAVE to know!  Babies are able to adjust their intake so they get what
they need.

I agree that a newly nursing premie needs more careful assessment than a
healthy full-term baby.  Test weights and creamatocrits could be really
useful, especially if they demonstrated that the mom didn't need to add
formula or fortifier.  But for a thriving baby, the good old rule of "watch
the baby" really is all the mother needs.

The challenge for us as breastfeeding helpers is to take what we have learned
from our reading and what we observe from our skilled assessment of the
nursing dyad and package it convincingly, so as to build the mother's
confidence in herself and her baby and in the amazing female power of
lactation.

Cheers,
Chris Mulford, RN, IBCLC
Swarthmore  PA  (eastern USA)

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