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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