To Donna's client who wondered whether the scale was measuring a solid or a
fluid 3 oz - why does it matter?  Three ounces of water weighs around 85
grams.  Three ounces of butter weighs about 85 grams.   Three ounces of
flour weighs 85 grams.  Three ounces of lead weighs 85 grams too.  But if
you fill a fluid measuring cup with flour to the 3 ounce mark and then weigh
it, it will weigh a lot less.  The specific gravity of flour is less than
water, which is a fancy way of saying that flour weighs less per volume than
does water.  So does butter, which is why it collects on the surface of warm
liquid.  If you want to see how big three ounces of flour is, you will need
to put your large measuring cup on a kitchen scale (something every home in
Europe has, but few in the US, showing up another difference in how we use
measures when cooking), then tare the scale with the cup on it, and start
pouring in flour until the scale reads 3 ounces.  
When the scale shows that a baby's weight has increased by three ounces from
before to after a feed, if you did the weighing properly that should mean
that the baby transferred about three ounces of milk from breast to gut.
Breastmilk has an average specific gravity very close to water, so we use
fluid volume and weight interchangeably.  BUT, the higher the fat content,
the less the specific gravity.  This means that if you see a baby
transferring only a fraction of an ounce toward the end of a feed, it could
still be a larger volume than you think, and certainly a higher calorie
content, because of the rise in fat content during the feed itself.  The
tail end of the feed doesn't weigh as much as the beginning of the feed
does, per volume, but it is denser in calories.

This is the major limitation of using a scale in assessing intake.  One
ounce of breastmilk is not a fixed quantity.  It weighs the same, an ounce
is an ounce, but that ounce doesn't consist of the same thing from the start
to the finish of a feed.  All the scale can tell you is the weight change in
the baby.  It can't possibly tell you what the calorie density of the feed
was, what proportion of the milk transferred was cream and what proportion
was water, or casein or whey.  And it can't tell you whether the baby is
content after receiving that number of ounces.

Fortunately we have other ways of telling whether a baby is satisfied for
the most part, the simplest of which is to look at the baby.  I am well
aware that the cases in which scales are a necessary adjunct to visual
observation are precisely those in which we may not be able to trust the
baby to protest at too little food, nor to have the stamina to take in
sufficient milk even if it is available.  Pia's daughter is a good example
as well, as it points out how very unusual the need for a scale is.  How
many of us see babies like that regularly in our practices?  I don't see
even one per year.  For the vast majority of babies, I feel we would be
doing them and their mothers a huge favor if we encouraged mothers to look
at growth over the longer term, week to week rather than feed to feed, and
to trust their babies to tell them if something is amiss.

This week I have actually met a mother whose life would be much easier if we
could get an electronic scale into her home for a few days, but it seems not
to be possible since there is nowhere to loan or rent one from (long story
and I don't have permission to tell it here) AND I have heard of a mother in
another part of Europe who has been doing pre- and postfeed weights with
every feed, at home, on her 3 week old healthy term infant, and it sounds
like what she needs is a peer supporter who is secure about breastfeeding
who could, for starters, go with her to the scale rental place and return
the blasted thing.  I consider **both** of these to be examples of scale
misuse.

Rachel Myr
Kristiansand, Norway  where I am now going to do some baking after
converting the measures in my US cookbook to metric weights so I can be sure
the cookies turn out right :-)

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