Slide 2
The benefits of breastfeeding have been well established. Breastfeeding
provides complete nutrition for the newborn for at least 4–6 months and
can provide a significant proportion of nutritional needs up to 1 year of
life. Breastfeeding also provides significant protection against
infectious morbidity and mortality from gastrointestinal infections, lower
respiratory infections, otitis media and meningitis, most likely because
of the presence of numerous immunologic factors in breastmilk. Newborn
mortality in general is increased 3-5 fold in the absence of
breastfeeding. Exclusive breastfeeding also reduces exposure to waterborne
pathogens in areas where the water supply is unsafe.
Slide 3
For the mother, breastfeeding delays the return of fertility. This
delay helps space pregnancies and allows the mother to recover from blood
loss associated with childbirth. In both cases, the woman has a longer
time to recover from the physical demands of pregnancy. Breastfeeding also
promotes mother-newborn bonding and is the least expensive alternative for
newborn feeding.
Slide 4
The objectives of this presentation are first to review the evidence
linking breastfeeding to mother-to-child transmission of HIV; second to
discuss the possible effects of breastfeeding on the health of
HIV-positive mothers; and finally to discuss interventions that may reduce
the risk of mother-to-child transmission through breastfeeding.
Slide 5
This table shows the timing and baseline rate of MTCT in three
different groups of women: those not breastfeeding at all, those
breastfeeding through the first 6 months of the newborn’s life, and
those breastfeeding through 18-24 months of life. It is thought that
breastfeeding may be responsible for approximately one half of the MTCT
that occurs throughout the world. Out of every 100 newborns born to
mothers with HIV, 5–10 are infected through breastfeeding.
Slide 6
This graph shows the cumulative rates of mother-to-child transmission
in several African studies. There are steep increases in newborn infection
rates in the first 1-2 months of life. These increases are probably due to
transmission during the intrapartum period, but may also be due to early
breastfeeding transmission. Transmission continues to increase as long as
breastfeeding continues.
Slide 7
The magnitude of the risk of mother-to-child transmission through
breastfeeding has been assessed in several studies. An international
pooled analysis of four African and four European/American studies found
an overall transmission rate of 3.2 per 100 child-years of breastfeeding.
Late postpartum transmission did not occur in newborns who were not
breastfed. To avoid confusing rates of transmission through breastfeeding
with transmission during childbirth, these studies included only those
newborns who were HIV-uninfected at 2 1/2 months old. This analysis,
therefore, underestimates the transmission that occurs during early
breastfeeding. Most transmission through breastfeeding occurred after 6
months.
Slide 8
In a large prospective cohort study in Malawi, the rate of
breastfeeding transmission was more than twice as high than the rate in
the international pooled analysis — 6.9 per 100 child-years of
breastfeeding. In this study as well, very early breastfeeding
transmission was missed because only newborns who were HIV-uninfected at 1
month were included. Unlike the pooled analysis, however, the Malawi study
found that risk of transmission was highest in the first months of
breastfeeding, but continued throughout the entire breastfeeding period.
Slide 9
Women who have acute or primary HIV infection are at higher risk of
transmitting HIV through breastfeeding than women with chronic or
established infection. This elevated risk is most likely because of the
high level of plasma viremia that is present during early acute infection.
A meta-analysis of breastfeeding transmission studies reported in 1992
found a transmission rate of approximately 29% when the mother had acute
HIV infection. This information has significant implications for
prevention. It reinforces the importance of prevention counseling if a
woman has had a negative HIV test early in pregnancy. Male or female
condom use should be encouraged throughout pregnancy and during
breastfeeding. It is important to emphasize that a negative HIV test does
not mean that she cannot become infected!
Slide 10
A number of variables may affect the risk of transmission with
breastmilk. In addition to new or acute HIV infection, advanced HIV
infection in the mother increases risk of transmission. High plasma viral
load, found in both acute and advanced infection, and low CD4 cell counts
seen in advanced HIV increase the risk for transmission with breastmilk.
Breastmilk viral load has also been identified as a risk factor. Although
higher viral loads in breastmilk are usually found when plasma viral load
is also increased, levels of HIV in breastmilk may be independently
increased in the presence of inflammatory breast conditions. These
conditions, including mastitis and breast abscess, are associated with
increased risk of transmission. Cracked nipples during breastfeeding also
increase risk. Although data are limited, the presence of HIV-DNA in
breastmilk has been correlated with vitamin A deficiency in the mother,
suggesting that vitamin A deficiency may also increase risk of
transmission with breastfeeding.
Slide 11
There are fewer data about the influence of newborn factors on the risk
of breastmilk transmission. Oral, esophageal or other gastrointestinal
lesions from thrush, trauma or other infection may result in mucosal
defects that could provide a portal of entry for the virus. The presence
of preterm birth and low birth weight as well as certain nutritional
deficiencies may affect immune system development and the integrity of
epithelial surfaces from the mouth through the intestinal tract.
Therefore, these conditions may also increase risk of breastmilk
transmission. There is also evidence that breastfeeding characteristics
related to the duration and pattern of breastfeeding affect transmission
risk. HIV has been identified in both cell-associated and cell-free
compartments of breastmilk, although it is not known if either has a more
dominant role in transmission. Colostrum has a greater concentration of
cells and immunoglobulins than more mature milk, but it is not clear if
the risk of transmission from colostrum is greater than, less than or
equal to the risk from later breastfeeding. As already mentioned, the
Malawi study found that the rate of transmission was greatest in the first
months of breastfeeding, but the international pooled analysis found that
most transmissions occurred after 6 months. Both found that transmissions
continued to occur for the duration of breastfeeding. A more recent study
has found significant differences in transmission between exclusively
breastfed newborns as compared to those fed with a mixture of breastmilk
and other solids or liquids.
Slide 12
This slide shows the cumulative risk of breastmilk transmission over
time with continued breastfeeding as found in the Malawi study. It is
important to note that in this study population, supplemental foods were
introduced at an average of 4 months of age.
Slide 13
A randomized clinical trial of breastfeeding versus formula feeding was
conducted in Nairobi, Kenya. HIV-positive mothers and their newborns were
randomized to one of these two newborn feeding groups with the objective
of comparing newborn HIV infection and death during the first 2 years of
life between the two groups. Although 96% of those assigned to the
breastfeeding group did in fact breastfeed their newborns, only 70% of
those assigned to the formula group completely avoided use of
breastfeeding; women assigned to the formula group often experienced
pressure from their families or from the community to breastfeed and were
sometimes concerned about maintaining confidentiality of their HIV status.
With a median of 24 months followup, the cumulative risk of newborn HIV
infection was 36.7% in those assigned to breastfeeding as compared to
20.5% in those assigned to formula, a statistically significant
difference.
Slide 14
This difference means that the estimated breastmilk transmission rate
is 16.2% in the first 2 years of life. Breastmilk accounted for 44% of all
newborn infections among those exposed to breastmilk. Because more than
one quarter of the women assigned to the formula group also breastfed to
some degree, this breastmilk transmission rate is an underestimate. In
this clinical trial, the data suggest that most breastmilk transmission
occurs during the early months of breastfeeding. 75% of the difference in
infection risk between the two groups occurred by 6 months of life.
Ongoing transmission through breastmilk, however, was observed throughout
the duration of exposure. The mortality rate at 2 years in all infants was
not significantly different between the breastfed and formula-fed
newborns. However, only 58% of women in the breastfeeding group had an
infant who was alive at 2 years and free from HIV infection, as compared
to 70% of women in the formula group. This study may not be directly
applicable to all low-resource settings. Women in the formula group had
access to municipal-treated water, were given free formula and taught how
to prepare it safely. Women in the breastfeeding group also introduced
weaning foods at a median time of 3.8 months, with only 62% exclusively
breastfeeding at 3 months and only 9% at 6 months. As we shall see, the
pattern of breastfeeding may play a significant role in the risk of HIV
transmission.
Slide 15
Exclusive breastfeeding is defined as the use of breastmilk alone for
newborn nutrition. Mixed feeding involves the use of breastmilk along with
other foods or liquids, which include water or a glucose-water solution,
weak tea, formula, cereal or porridge, fruits and vegetables. Exclusive
breastfeeding has been associated with reduced incidence of diarrhea,
respiratory illness and allergy, as well as reduced neonatal mortality, as
compared to mixed feeding. Although the mechanisms through which exclusive
breastfeeding may be safer than mixed feeding are not well understood, a
leading hypothesis is that contaminated fluids and foods may cause damage
to the bowel in newborns, thereby facilitating entry of HIV in breastmilk
into newborn tissues.
Slide 16
A prospective cohort study conducted in Durban, South Africa, examined
the risk of HIV transmission by newborn feeding modality, including the
use of exclusive breastfeeding versus mixed feeding. The study involved a
total of 551 HIV-positive pregnant women and their newborns. HIV
transmission was compared among three groups of women: those who never
breastfed their newborns, those who breastfed their newborns exclusively
for 3 months or more and those who gave their newborns a mixture of
breastmilk and other liquids or solids or had exclusively breastfed for
periods of less than 3 months. Women were educated about the risks of
transmission through breastmilk and about the other health benefits of
breastfeeding, and were allowed to make their own decisions about choice
of newborn feeding.
Slide 17
The results of this study found that newborns who were exclusively
breastfed had no excess risk of HIV infection over 6 months as compared to
those newborns who were never breastfed. Newborns who were fed with a
mixture of breastmilk and other foods or liquids were at the greatest risk
of HIV transmission. After newborns who were in the exclusive
breastfeeding group began to be fed other foods or liquids, new infections
began to occur in those still also receiving breastmilk. The risk of
transmission by 15 months, however, was still greatest in those newborns
who had never exclusively breastfed or had done so for less than 3 months.
These findings were unchanged after adjusting for many other variables
that have previously been found to influence HIV transmission in the
perinatal period.
Slide 18
A recent analysis has raised concerns that breastfeeding may have an
adverse effect on maternal health in HIV-positive women. HIV-positive
women who participated in the randomized clinical trial of breastfeeding
versus formula feeding in Kenya that has already been discussed were
followed for 2 years after childbirth. Those who had been assigned to the
breastfeeding group had a 3-fold increased mortality during this period of
followup as compared to those who had been assigned to the formula group.
Furthermore, after controlling for HIV status in the newborn, the newborns
of mothers who died had an 8-fold increase in the likelihood of subsequent
death.
Slide 19
There was no evidence, however, of increased mortality or morbidity 11
months after childbirth in women who breastfed who were enrolled in a
randomized vitamin A supplementation study in South Africa when compared
to women who never breastfed.
Slide 20
Neither of these two studies was designed to specifically address the
issue of maternal mortality associated with breastfeeding. More study is
needed before we can draw definite conclusions about whether there is a
relationship and what that relationship is. The different results of these
studies, however, raise two issues. What is the role of maternal
nutritional status in determining the effect of breastfeeding on maternal
health? Women in the Kenya study were more likely to be anemic than those
in the South African study. Anemia is a marker for poor nutrition. In the
Kenya study, women who breastfed had greater weight loss than those in the
formula group. Also, there was a significant association between weight
loss during followup and maternal mortality. It is possible that the
combined metabolic demands of HIV and breastfeeding in terms of energy and
nutrient stores may result in substantial nutritional impairment,
especially in those women who are already affected by malnutrition.
Slide 21
Secondly, what is the role of maternal immune status in determining the
effect of breastfeeding on maternal health? In the Kenya study, maternal
deaths were associated with lower CD4 counts and higher HIV viral load at
enrollment, identifying a group of women with poorer immune status to
begin with as compared to those women analyzed in the South African study.
Although precise information of causes of maternal death in the Kenya
study was missing, available information suggests that in most cases
mortality was related to HIV/AIDS.
Slide 22
Although neither of these two studies give us definitive answers, the
effect of breastfeeding on maternal health is an important issue, not only
for HIV-positive mothers, but also for their newborns. Findings from other
studies in Africa have shown a 3- to 4-fold increased risk of death in
children whose mothers have died. The graph on this slide demonstrates the
differences in newborn mortality per 100 live births between those born to
HIV-positive and HIV-negative mothers in several different African
settings and in Haiti. The differences in mortality relate not only to
mortality from HIV transmission to the newborns, but also to the adverse
effects on newborn health and mortality when mothers are ill and die from
HIV.
Slide 23
The most effective way to prevent HIV transmission by breastfeeding is
by preventing HIV infection in women of childbearing age. Because women
who are newly infected during pregnancy or breastfeeding are at increased
risk for mother-to-child transmission with breastmilk, special education
and counseling about safer sexual and drug-using practices during
pregnancy and lactation should be emphasized. As we have become aware of
both the risk of MTCT and also specific interventions to prevent
mother-to-child transmission of HIV, it has become increasingly important
to identify HIV infection in women who are pregnant or considering
pregnancy. HIV testing should be done in the context of counseling and
should be voluntary.
Slide 24
Specific interventions to help prevent HIV transmission by
breastfeeding are discussed in this and the next several slides. Women who
are HIV-negative or who do not know their HIV status should exclusively
breastfeed for 6 months to give their newborn the greatest benefits from
breastfeeding and limit the potential risk from unrecognized HIV in the
women who have not been tested. Women who are HIV-positive should avoid
breastfeeding WHEN replacement feeding is acceptable, feasible,
affordable, sustainable and safe. When these mothers choose not to
breastfeed, they should be given specific guidance and support to ensure
that their newborns receive adequate and appropriate nutrition.
HIV-positive women who choose to breastfeed or for whom breastfeeding is
the safest and most appropriate alternative should be encouraged to
breastfeed exclusively up to 6 months of the newborn’s life. This takes
advantage of the benefits from breatfeeding which are greatest in the
first 6 months of life and avoids the risks of replacement feeding, which
are less as the newborn matures. Limiting breastfeeding to 6 months also
avoids the risk of HIV transmission which continues with increasing
duration of breastfeeding. Women should be educated about proper
breastfeeding techniques, including proper attachment of the newborn to
the nipples and frequent breast emptying to promote good breast health.
Breastfeeding mothers should be taught to prevent, recognize and promptly
seek treatment for mastitis, breast abscess, cracked nipples or other
breast lesions that might increase risk of transmission. Similarly, the
newborn’s mouth or pharynx should be checked for oral thrush or other
oral lesions and these should be treated.
Slide 25
Good hygiene and food safety should be taught and promoted both to
maintain maternal health and to ensure the safety of replacement feeding
when it occurs. Improving the nutritional status of pregnant and lactating
mothers can improve the mothers’ health and may help prevent
transmission through breastmilk. Vitamin E supplements were found to
reduce mastitis risk in a Tanzanian study. Iron supplements or ingestion
of iron-rich foods should be encouraged because maternal iron status may
be depleted with lactation, which can contribute to anemia, which, in
turn, increases the risk of progression and death in HIV-positive women.
Slide 26
Finally, when breastfeeding is practiced, the transition from exclusive
breastfeeding to full replacement feeding or total weaning should be kept
as short as possible. Again, mothers will need guidance after stopping
breastfeeding to ensure adequate newborn nutrition, as well as counseling
and support to maintain breast health and decrease the psychological
consequences of rapid weaning.
Slide 27
Several short course antiretroviral regimens have now been proven
effective in reducing MTCT in both breastfeeding and nonbreastfeeding
populations. Although followup of breastfeeding newborns exposed to these
regimens continues to show differences in infection rates compared to
those exposed to a comparison agent or placebo, efficacy is less than in
nonbreastfeeding populations and differences begin to wane with longer
followup. There is no evidence that the regimens studied to date decrease
the risk of MTCT from breastfeeding.
Slide 28
It should be restated that women who do not breastfeed in areas where
this is the accepted norm may face social stigma and not breastfeeding may
arouse suspicion or even violence. Furthermore, strong cultural pressures
to breastfeed along with a desire to protect the newborn as much as
possible by not breastfeeding may increase the practice of mixed feeding
by HIV-positive mothers, therefore actually increasing the risk to their
newborns.
Slide 29
Further areas for research include clinical trials to determine the
role of antiretroviral therapy given to the newborn and/or the mother for
more prolonged periods postpartum to prevent MTCT through breastfeeding.
In addition, research is needed to determine the feasibility and safety of
heat treating breastmilk expressed at home to inactivate HIV. Ultimately,
immune-based interventions, including both passive immune therapy and
vaccines, are urgently needed and carry the greatest hopes for the future.
Slide 30
In summary, all HIV-positive pregnant women should receive counseling
that includes general information about the risks and benefits of
different newborn feeding options and specific guidance to help the mother
choose the most suitable option for her individual situation. She should
be given support for the alternative she chooses. It is also important
that local assessments be conducted to identify the range of newborn
feeding options that are acceptable, feasible, affordable, sustainable and
safe in different locations. Information and education about MTCT of HIV
in general and with breastfeeding should also be directed to the general
public, communities and families. This education will help fight stigma
and discrimination against women and mothers with HIV infection and can
help build support for safer newborn feeding practices. Prevailing
cultural practices concerning newborn feeding and the stigma and suspicion
that often accompany any changes in those practices remain a major barrier
to safer newborn feeding.
