Re:  Breastfeeding and the relation to asthma - a summary I wrote recently:

There are several recently published studies that appear to show
breastfeeding as related to an increase in the risk for asthma, but this can
be misleading.  I am not qualified to analyze these studies in detail, but I
can comment on some items of interests from looking at the abstracts
available on PubMed www.ncbi.nlm.nih.gov/entrez/ .

In the last year alone PubMed lists almost twenty articles related to asthma
and breastfeeding, so I have restricted myself to some of these studies and
have only included excerpts (the full abstracts are available at PubMed;
search "breastfeeding and asthma").  In reviewing these abstracts I
identified some points which would need to be considered to do a thorough
review of the relevancy of the study results from the full published
research article; the degree to which breastfeeding is defined and
categorized in terms of duration, when and what complementary foods were
introduced, the design of the study (such as questionnaire, record review,
or current medical findings), parental history as a confounding variable,
and the definition of asthma as distict from transient respiratory
infections. Selection bias may also be present, since it has been accepted
for years that breastfeeding may reduce allergy so mothers with asthma may
disproportionately have chosen to breastfeed, and to breastfeed longer for
this reason. One study noted a correlation between the father's educational
level and asthma , yet it is difficult to see any relation - this
illustrates why correlation cannot be considered to equal causation, without
other studies.

The second, third and fourth study I have listed found some negative
relation to breastfeeding and asthma, with two studies clearly stating this
relation was only found in the presence of maternal asthma.  The fifth study
examines the possible relationship of allergic mothers passing allergens to
their children through the breastmilk which may 'teach' an allergic
response. However, the other studies all strongly support the finding that
breastfeeding reduces the risk of asthma, especially in the presence of a
family history of this disease (one of these latter studies found paternal
asthma to be a stronger risk factor than maternal asthma, which factor was
apparently not even considered in other studies).

This excerpt from the first article very effectively sums up the current
situation concerning asthma as it relates to breastfeeding:
Association between breast feeding and asthma in 6 year old children:
findings of a prospective birth cohort study (British Medical Journal 1999);
? "Asthma is the leading cause of admission to hospital in Australian
children and its prevalence is increasing
? Whether breast feeding protects against asthma or atopy, or both, is
controversial
? Asthma is a complex disease, and the relative risks between breast feeding
and asthma or atopy are unlikely to be large; this suggests the need for
investigation in a large prospective birth cohort with timely assessment of
atopic outcomes and all relevant exposures
? Exclusive breast feeding for at least 4 months is associated with a
significant reduction in the risk of asthma and atopy at age 6 years and
with a significant delay in the age at onset of wheezing and asthma being
diagnosed by a doctor
Public health interventions to promote an increased duration of exclusive
breast feeding may help to reduce the morbidity and prevalence of childhood
asthma and atopy."

I have to conclude that the relation of breastfeeding as a protective or
risk factor in asthma is still controversial, and will remain so until a
long-term study is initiated that considers all of the many confounding
variables.  Even if a strong correlation between long-term breastfeeding and
asthma were to be consistently found there are many other known benefits to
breastfeeding, the incidence of asthma in non-breastfed children is
significant, and there may be other related factors which might be altered
to minimize the effect (i.e. avoidance of allergens in maternal diet.)
Currently, a far greater number of research studies support the duration of
breastfeeding as positively linked with reducing the risk of a child
developing asthma, rather than increasing the risk. These studies conclude
that breastfeeding has the potential to significantly reduce the incidence
and/or severity of asthma and allergic diseases.

If you want the journal citations, please email me privately (this is too
long!).

Michelle Bentley CLE, LLL

----- Original Message -----
From: "Megan Geiszler" <[log in to unmask]>
Sent: Wednesday, January 23, 2002 5:43 PM
Subject: Resubmittal "Breastfeeding and allergy development"

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