AAAGH! My beautiful post was all besmirched with erroneous letters and
numbers! I'll try again.
How much milk does a baby need? As I remember, this question was asked
about *newborns*. This is really important to remember.
Pat Young says times the baby’s weight in pounds gives the number of ounces
needed per day.
Gonneke van Veldhuizen says 150 cc per kg per day (which is about the same as
Pat’s rule---2.47 times the weight in pounds.)
Marian Rigney has a more detailed schedule for the first week, taken from a
recent Textbook of Neonatal Medicine.
30 mls /kg on Day 1
60 mls /kg on Day 2
90 mls /kg on Day 3
120 mls /kg on Day 4
130 mls /kg on Day 5
140 mls /kg on Day 6
150 mls /kg from Day 7
The mathematical symmetry of this schedule makes me wonder whether the author
began with the 150 cc per kg figure and calculated backwards to zero on Day
0. But when you compare it to work by Neville et al, it’s not far off the
mark.
Neville’s measurements of milk output in eleven women over the first eight
days are shown in graphs on pp 269 and 270 of Clinics in Perinatology, June
1999. Her description says, 'Milk transfer, originally less than 100 ml per
day, began to increase about 36 hours postpartum, continued dramatically
upward for about 48 hours, and then leveled off [at 600 ml/day] after about 4
days.' 600 ml/day would be 150 ml/kg for a 4 kg (or 8 # 13 oz) baby.
Marian Rigney also gave us a quote from that neonatology textbook: 'Healthy
bottle fed infants will also 'know' how much fluid they need and should be
allowed to consume milk when they want it, to the volume that satisfies
them.'
I have some problems with this quote. I assume that a healthy infant in its
mother’s arms feels thirst and probably feels hunger, and from its rooting
behavior I guess that it almost surely feels some kind of need to suck. If
the baby is offered a breast and is able to attach effectively and is left to
its own devices, then suckling will continue until the baby stops. Why does
the babys top? Presumably because it is no longer thirsty or hungry, or no
longer needs to suck, or has become too tired to suckle, or has fallen
asleep. From my observation of newborns, I think they mostly stop nursing
because they fall asleep and release the breast. (CCK at work!) Then when
they wake up, which could be in 1-2 minutes or in 10-20 minutes or in some
number of hours, they seek the breast again, for some or all of the reasons I
listed before. Also from time to time they are quietly alert and ready to
interact visually with their environment. And so life goes on.
But this textbook quote is assuming that *thirst* is the only motivation for
feeding/suckling (infants 'know’ how much fluid they need). It also assumes
that whatever is in the bottle has the correct amount of nutrients per ml of
water so that satisfying thirst automatically satisfies the baby‘s needs for
carbohydrates, fats, and protein. Also it assumes that any presumed need of
the baby to suck or suckle is satisfied by the amount of sucking they get
from the bottle. That’s a lot of assumptions.
Magda Sachs questions whether we really know enough to come up with *any*
mathematical formula to guide us about the proper amount for babies to eat or
the right rate for them to grow. Why not look at the baby…and the baby’s
parents…and the baby’s siblings, if any…and the baby‘s general health…and
the baby’s environment…and the mother’s environment…etc? I agree. Any
assessment of a baby has to look at the whole baby. If the baby’s growth
rate is slowing down relative to other babies of the same age, it might mean
that the baby has a problem---it doesn’t mean automatically that the baby
needs to eat more. Instead, it means that the grownups who are responsible
for that baby need to take a look and see what’s going on. And this is
assuming that the chart that shows how other babies of the same age were
growing is based on babies who were being fed the same stuff in the
sameway---exclusively breastfed babies compared to other exclusively
breastfed babies, for instance.
My main reason for writing, though, is to put out a caution about that 150 ml
per kg per day rule. That rule works out to 750 ml for a 5 kilo baby, or 25
ounces for an 11 pound baby. Studies of formula-fed babies from Fomon‘s 1974
text on infant nutrition did show that formula babies, who started out after
birth taking in more than 110 calories/kg/day, stabilized their intake at 100
calories per kg per day around the age of four months. This means that their
formula intake increased as they gained weight. But breastfed babies are
different.
The average milk intake for exclusively breastfed babies published by Neville
et al in 1988 is around 600 to 800 mls per day over the first eight months.
As the baby gets older, you might think it would require more milk---like the
formula fed baby---because its weight is increasing. However, what studies
have shown is that as the breastfed baby gets older, the caloric intake per
unit of weight decreases.
150 ml of milk contains roughly 100 calories. According to a paper presented
by Garza, Stuff, and Butte in 1986, a six week old breastfed baby takes in
about 100 calories (150 ml) per kg; by 2 months the baby is taking in about
80 calories (120 ml) per kg. From around 3 months the calories per kg
stabilizes at about 70 (105ml/kg), and the baby‘s volume intake also
stabilizes somewhere around 750 mls per day.
It is really important that we understand this difference before we advise
moms who are going to work. Otherwise they’ll multiply their (older) baby’s
weight in pounds by oz or in kg by 150 ml, and they’ll be intimidated at the
amount of milk the rule says they have to supply. For an 8 kg baby that
would be 1200 ml per day, or for a 17# 9 oz baby, 40 ounces. Combine a
mother who is anxious about leaving her baby, a baby who is fussy being in a
new place without its mom, a caregiver who thinks formula will 'satisfy'
babies better, and an unrealistic rule for how much milk the baby requires
for its weight, and you've got a recipe for unnecessary supplementation.
Chris
with fingers crossed in Swarthmore PA
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