Dear all:

Sometimes I don't realize what is and is not common knowledge coming from a different 
background from many LCs.  I did my doctoral studies in a Nutritional Sciences Department that 
had a physical anthropologist and I guess I just assumed that this was part of the training for most 
RDs and for medical staff as well. We played with skin calipers, hanging scales, digital scales, 
length boards, height boards, bioelectrical impedence devices, and the RDs (we weren't included 
in this) did the underwater weighing. We did neat little exericises to determine accuracy, reliability 
& dependability.  All of these are quite important when taking measurements.  

I got to hear the official version of how test weighing came about and the dark ages of what came 
before.  Test weighing was a result of a considerable amount of work on getting accurate and 
reliable measurements.  Dependability is determined by such factors as time of day, vigor of the 
feeding, etc.

So, the history of test weighing is grounded in the problems of the ratio of the infant's size 
compared to the intake as well as the fact that infants wiggle.  A fair amount of research went into 
conquering this problem.  The end result was that the only way that you could compensate for the 
wiggle factor in infants in terms of measuring intake was to get a triple average.  This used to be 
done by hand.  Researchers would weigh the infant 3 x before the feed and 3 x after the feed.  
Now the new scales do this electronically. In anthropometric circles of research all of this is well 
known.  I am astounded that anyone even dared to publish something as silly as comparing 
eyeballing bottle intake with a fair amount of research on triple average weights.  Since this was so 
thoroughly covered in my doctoral studies I thought it was common knowledge and dumped my 
files on the topic about 5 years after I finished my PhD.

What is important for us as clinicians is not the accuracy and precision of weighing scales which 
are thoroughly documented despite some recent sophmoric research that was totally unfounded in 
using eyeballing bottle intake as a gold standard (my former professors will be appalled).  What is 
important to us is the dependability. When we weigh the baby and how that compares with the 
usual feed.  This is the same problem with ANY measurement we would take on the baby whether 
it is counting swallows, listening for swallow noises, or any other clinical observation.  Any 
observation we make on the baby is but a slice of the picture. So, it seems to me that any criticism 
of using a digital scale to estimate intake could be applied to ANY technique that one uses to 
estimate intake.  How can you extrapolate to the entire picture your one observation of the suck 
swallow pattern?

In this regard, I have the total luxury of having abandoned my former interesting, but high stress 
time intensive work in international nutrition for more control over my time.  I could make tons 
more money in Manhattan if I were willing to pack in the clients on a tighter schedule, but I'm no 
longer at this stage in life willing to do so.  If I lived in a less densely populated area, I wouldn't 
survive economically.  So, I can tell you that there is a huge difference in the picture you get if you 
wait for the baby to feed rather than nudging them to feed according to the LC's schedule.  The 
most extreme case I remember was a baby that should have been ready to feed when I arrived and 
wasn't. Scale or observation, I'm sure all of you would have concluded the baby was lethargic and 
not feeding well.  Had I not had the luxury of spending a good 3 hours with this mom, I would not 
have observed and measured a fabulous feeding about 2-1/2 hours after I arrived.  It changed the 
equation entirely.  This was not dependent on the tool used to estimate intake - it was merely 
being able to spend time with the mom.  So, I conclude that for babies at risk - all should be 
triaged into a situation where more extensive evaluations can be done be it history taking, regular 
follow up, measurement of intake or any other tools we have to analyze a problem in more depth.

As a side note, one of my professors confessed the details of the absurdity of other measures that 
were used to determine the amount of milk produced back in the earlier days of trying to 
guestimate milk production (which I consider very different from infant intake).  Apparently they 
used conical devices that they placed on women's breasts which had been calibrated to guestimate 
the volume of milk that could be held in that particular volume of breast tissue.  We all know how 
variable breast tissue is in terms of the ratio of fat to glandular tissue so you can imagine how 
incredibly inaccurate this method was.

Now I think of the absurdity of sizing a woman's breasts for breast shields for the pump by 
looking at the resting breast.  I saw some device that was intended to measure nipple size for 
such sizing. Well intended. But when you actually observe women pumping again and again and 
again, you realize nipple size has nothing to do with the size of the breast shield that will be 
comfortable.

So, to conclude, the research is pretty solid and vast (in at least the international nutrition circles 
that came from) that the test weighing with triple average digital scales is the most accurate and 
precise method, BUT

1) not all circumstances require that degree of accuracy 
2) any method of estimating intake be it clinical observation or test weighing requires judgement 
about the dependability of the measurements/observations taken
3) the use of  data from any source be it test weighing or clinical observation is highly dependent 
upon the skills of the user

Best regards, Susan Burger

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