Emma
You pose a good question. In fact, the research
is a little conflicting. A 1999 Malawian paper
showed that the risk of HIV-transmission due to
breastfeeding decreased over time. Incidence per
month was 0.7% from 1-5 months, 0.6% from 6-11
months and 0.3% from 12-17 months.
"Breastfeeding" was not defined, but almost
certainly meant predominant breastfeeding, ie the
baby's main source of nutrition would have been
breastfeeding with little quantities of
water/teas and maybe early solid foods before 6
months - it's very unlikely that any babies would
have received any formula at all in Malawi in 1999.
But several later studies have looked at what
happens during _exclusive_ breastfeeding during
the early months, and risk of transmission
later. There have only been two papers which
have published HIV transmission rates for babies
older than 6 months who had been exclusively
breastfed for _three_ months. In 1999 and 2005,
research from South Africa and Zimbabwe showed
that the risk of HIV transmission when
breastfeeding was practised exclusively from
birth to 3 months was 0% and 1.3% respectively
(when tested at 6 months). Exclusive
breastfeeding to 3 months also conferred a 60%
reduced risk of transmission during breastfeeding
from 3 to 15-18 months (5.3% and 5.6%
respectively) compared to 9.8% and 9.5% for
babies who had been mixed-fed in the first three
months. However, the Zimbabwean authors did
conclude that 68% of transmission had occurred as
a result of breastfeeding beyond 6 months. To
offset this, the mortality rate at 18 months for
the EBF Zimbabwean infants, whether or not
HIV-infected, was less than half that of the
group who had been mixed-fed from birth. Of
note, in the Zimbabwean study, one "lapse" in
feeding of non-breastmilk liquids was permitted
in the definition of "exclusive breastfeeding".
A further study by the South African group was
published in the March 2007 Lancet. 83% of
HIV-infected mothers were supported to
exclusively breastfeed to 6 months (although a
lapse of 3 days’ mixed feeding - water, solids or
formula - was permitted in this definition). The
risk of transmission through breastfeeding was 4%
and cumulative 3-month mortality was 6.1% vs
15.1% for infants given replacement feeds,
showing a clear relationship between replacement
feeding and increased mortality.
The risk of HIV-transmission if breastfeeding
continued beyond 3, 4, 5 or 6 months had led to
recommendations for "early cessation" of
breastfeeding. But several studies presented or
published in the last couple of years have shown
clearly that while the risk of
breastfeeding-associated transmission is avoided
by premature weaning, the risk of malnutrition
and mortality is increased, so that the gains on
the one hand are cancelled out by the losses on
the other. HIV and infant feeding experts are
therefore beginning to identify HIV-free survival
at 18-24 months as the main outcome measure,
rather than avoidance of HIV-transmission
alone. So far no study has shown any HIV-free
survival advantage to early weaning.
A recent follow-up paper to the EBF-for-6-months
research was very recently published, giving
"HIV-infection or death" outcomes for
breastfeeding beyond 6 months for those babies
who had been exclusively breastfed for 6
months. The authors were extremely careful, this
time, to define exclusive breastfeeding properly,
confirming "if an infant received water, nonhuman
milk or solids even for 1 day, the infant was
reclassified as mixed fed." Babies exclusively
breastfed for 6 months comprised 31% of the total
number, but the results were still unclear. The
wording in the paper says, "Among the infants
breastfed beyond 6 months of age, although the
differences in overall probability of death or
HIV infection between 7 and 18 months in these
three groups did not reach statistical
significance, those who were exclusively
breastfed in the first 6 months tended to do better than those mixed fed."
Refs:
Miotti PG, Taha TE, Kumwenda NI, Broadhead R,
Mtimavalye LA, Van der Hoeven L, Chiphangwi JD,
Liomba G, Biggar RJ. HIV transmission through
breastfeeding: a study in Malawi. JAMA. 1999 Aug 25;282(8):744-9.
Coutsoudis A, Pillay K, Spooner E, Kuhn L,
Coovadia HM. Influence of infant-feeding
patterns on early mother-to-child transmission of
HIV-1 in Durban, South Africa: a prospective
cohort study. South African Vitamin A Study
Group. Lancet. 1999 Aug 7;354(9177):471-6.
Iliff PJ, Piwoz EG, Tavengwa NV, Zunguza CD,
Marinda ET, Nathoo KJ, Moulton LH, Ward BJ, the
ZVITAMBO study group and Humphrey JH. Early
exclusive breastfeeding reduces the risk of
postnatal HIV-1 transmission and increases
HIV-free survival. AIDS 2005, 19:699–708.
Coutsoudis A, Pillay K, Kuhn L, Spooner E, Tsai
W-Y, Coovadia HM for the South African Vitamin A
Study Group. Method of feeding and transmission
of HIV-1 from mothers to children by 15 months of
age: prospective cohort study from Durban, South Africa. AIDS 2001;15:379-387.
Coovadia HM, Rollins NC, Bland RM, Little K,
Coutsoudis A, Bennish ML, Newell
M-L. Mother-to-child transmission of HIV-1
infection during exclusive breastfeeding in the
first 6 months of life: an intervention cohort
study. Lancet 2007 March 31;369:1107-16.
Rollins NC, Becquet R, Bland RM, Coutsoudis A,
Coovadia HM and Newell M-L. Infant feeding, HIV
transmission and mortality at 18 months: the need
for appropriate choices by mothers and
prioritization within programmes. AIDS 2008, 22:2349–2357.
I hope this helps.
Pamela Morrison IBCLC
Rustington, England
Co-coordinator, WABA Task Force on HIV and Breastfeeding
----------------------------------------
Sent: Wednesday, November 26, 2008 3:27 AM
Does anybody know why/have the data regarding the transmission rates of =
HIV
going UP after 6 months of exclusive BF ? I have seen the comments made
before that long-term or anything beyond 6 months of EBF puts the baby =
at a
*greater* risk for transmission. Evidently, I find this odd...
Emma Kwasnica, in Montreal
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