Thank you Barbie and Josefine for introducing this very important article
which appears in the Lancet, 7th August. I think the implications of this
research are vital to all of us as advocates of breastfeeding. Here are a
few more excerpts:
"Since the discovery that HIV-1 can be transmitted through breastfeeding,
several policy recommendations have been developed, which are expected to
have a global impact on maternal and infant health. Whether prevention of
HIV-1 infection through avoidance of breastfeeding will in practice outweigh
the adverse effects of not breastfeeding has yet to be discovered.
Breastfeeding by HIV-1-infected women in more-developed countries has
virtually ceased and in less-developed countries many thousands of
seropositive women and women who believe they may be HIV-1 infected are
expected to avoid breastfeeding. The cultural diffusion theory raises the
possibility that a loss of confidence in breastfeeding will spread to all
women....
"Analyses of HIV-1 transmission via breastmilk are flawed because they have
failed to account for the effects of different types of breastfeeding
practices: exclusive or mixed breastfeeding (without or with water, other
fluids, and foods that might contaminate and injure the immature
gastrointestinal tract). Two studies have attempted to examine the effect
of different breastfeeding patterns on mother-to-child transmission, but
both have limitations. The most widely quoted meta-analysis on the risks of
mother-to-child transmission by breastfeeding depended on studies with
small sample sizes, short breastfeeding durations, and studies that do not
distinguish exclusive from mixed breastfeeding.
We prospectively examined the impact of different patterns of breastfeeding
on mother-to-child transmission of HIV-1 at 3 months of age....
"The estimated proportion ..of infants HIV-1 infected by 3 months was
significantly lower for those exclusively breastfed to 3 months than in
those who received mixed feeding before 3 months (14·6% vs 24·1% ... exclusive
breastfeeding carried a significantly lower risk of HIV-1 transmission than
mixed feeding and a similar risk to no breastfeeding ..(18%)
"Our findings have important implications for prevention of
HIV-1 infection and infant-feeding policies in developing countries and
further research is essential. In the meantime, breastfeeding policies for
HIV-1-infected women require urgent review. If our findings are confirmed,
exclusive breastfeeding may offer HIV-1-infected women in developing
countries an affordable, culturally acceptable, and effective means of
reducing mother-to-child transmission of HIV-1 while maintaining the
overwhelming benefits of breastfeeding...
"Our results do not accord with conventional wisdom because they suggest that
the vertical transmission of HIV-1 through breastmilk is dependent on the
pattern of breastfeeding and not simply on all breastfeeding. Exclusive
breastfeeding carries a significantly lower risk (almost half the risk) of
mother-to-child transmission of HIV-1 than mixed feeding. Although the risks
of HIV-1 transmission associated with non-exclusive breastfeeding seem to be
substantial (risk of HIV-1 infection by 3 months was 24·1% in the
mixed-feeding group and 18·8% in the never-breastfed group, giving a
difference of 5·3% presumably due to postnatal infections), exclusive
breastfeeding does not seem to convey any excess risk of HIV-1 transmission
over formula feeding. Transmission rates by day 1 (about 6%), which reflect
in-utero infections only, were similar in the three feeding groups.
Therefore the groups did not differ initially in their risk of HIV-1
transmission. .. After exclusion of those already shown to be HIV-1 infected
at birth and therefore not at risk of postnatal infection, differences
between exclusive (8·3%) and mixed breastfeeding (19·9%) groups were greater. ..
"Among infants not already HIV-1 infected at birth, those who were
exclusively breastfed had a lower probability of infection than those never
breastfed. Although this difference was not significant, it raises a
possibility that virus acquired during delivery could have been neutralised
by immune factors present in breastmilk but not in formula feeds. Breastmilk
contains non-specific immune factors that have antiviral and anti-HIV-1
effects in vitro. These factors include secretory leucocyte protease
inhibitor,14 lactoferrin, complement, and glycosaminoglycan.15 The finding
that mixed feeding carries the highest risk is not surprising because the
beneficial immune factors of breastmilk are probably counteracted by damage
to the infant's gut by contaminants or allergens in mixed feeds.
Breastmilk contains growth factors, such as epidermal growth factor and
transforming growth factor ß, which may enhance the maturation of the gut
epithelial barrier, thus maintaining its integrity and hindering passage of
virus.16,17 Preble and Piwoz18 postulated that exclusive breastfeeding may
have lower risk of vertical transmission of HIV-1 than mixed feeding.
Ingestion of contaminated water, fluids, and food may lead to gut mucosal
injury and disruption of immune barriers. Since mixed feeding is unlikely to
involve hygienic food preparation practices, bacteria and other contaminants
may be introduced into the gut and result in inflammatory responses and
subsequent damage to the mucosa. HIV-1 is less likely to penetrate intact
and healthy gastrointestinal mucosa than damaged mucosa.... Once the
integrity of mucosal surfaces has been compromised by infection, allergens,
or trauma, the passage of HIV-1 across mucous membranes into body tissues is
facilitated."
Me now: Please could we think about the implications of this study as we
work to provide mothers with *informed* choices, and policy-makers and
healthcare providers with up-to-date and clear information about this tragic
and emotive dilemma.
Pamela Morrison IBCLC, Zimbabwe
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