Hi Liz,
My basis for this opinion comes from looking at other population studies
that have similar (retrospective designs) and then (usually much smaller)
studies from the same populations that have prospective designs. When you
have retrospective studies you underestimate the exposure to infant formula.
The CDC study asks parents to remember back a minimum of a year and a half
and a maximum of 3 years- we know that such retrospective designs does not
give accurate data on exclusivity (but does on any breastfeeding). And then
there's personal observation- just from the people I know very, very few
infants are not given infant formula at some point even when their mothers
are rabid breastfeeders. According to the US CDC data half of babies
breastfeeding at 6 months of age have never been exposed to infant formula,
not once in their life....that's an impressive stat, does that gel with your
experience??
Karleen Gribble
Australia


-----Original Message-----
From: Lactation Information and Discussion
[mailto:[log in to unmask]] On Behalf Of Elizabeth Brooks
Sent: Tuesday, 15 February 2011 1:35 PM
To: [log in to unmask]
Subject: Re: Medela, Advertising and commercialisation [and BF studies]

Karleen, I'm not a statistician nor epidemiologist.  But I took a look at
the CDC's survey methods used to collect the data to arrive at rates for BF
initation, exclusivity and duration (at
http://www.cdc.gov/breastfeeding/data/NIS_data/survey_methods.htm ) --
including the wording of the questions they used to collect the BF
data.  The qeustions were part of the [US] National Immunzation Survey. The
sample is pretty big:  "This nationwide survey provides current national,
state, and selected urban-area estimates of vaccination coverage rates for
U.S. children ages 19 to 35 months. Since July 2001, breastfeeding questions
have been asked on the NIS to assess the population's breastfeeding
practices."  When you look at the page above, the BF questions are listed
right there ... including how the wording was tweaked in different years to
"get at" that exclusivity notion.

I think the CDC (which does use statisticians and epidemiologists) would be
alarmed to realize they got it wrong by as much as 8 percentage points.
They report 13% exclusive BF at 6 months; your post suggests the number is
closer to 5%.  What is the basis for your conclusion that 5% is the more
accurate rate?

Liz Brooks JD IBCLC FILCA
Wyndmoor, PA, USA

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