Since the beginning of the HIV pandemic, almost 3 million children have died of AIDS. Another million children were estimated to be living with the disease at the end of 1997, half of them infected last year alone.
Most HIV-positive children acquire the virus from their mothers in the uterus, during labor and delivery, or through breast milk. Their numbers will continue to rise as the number of HIV-positive women of childbearing age increases. In a growing number of countries, HIV has already become the single greatest cause of child death, undermining decades of progress in child survival.
The majority of children infected with HIV live in low- and middle-income countries. This gap in mother-to-child HIV transmission between industrialized and non-industrialized countries continues to widen. For example, in France and the United States fewer than 5 percent of children born to HIV-positive women in 1997 were infected with the virus. In non-industrialized countries, the average was between 25 percent and 35 percent.1 There are two major reasons for this difference--access to drugs for reducing mother-to-child transmission and breast-feeding practices.
AZT and Access
Four years ago research in the United States and Europe showed that giving an antiretroviral drug, zidovudine (AZT), to pregnant women during pregnancy and delivery and to their infants after birth could cut HIV transmission from mother to child by as much as two-thirds.2 This quickly became common practice in industrialized countries.
That particular regimen of AZT has not been available to women in resource-constrained settings, however, because of its complexity and cost. It is difficult to administer, involving regular drug taking over several months and intravenous administration during delivery. It is also prohibitively expensive, at approximately U.S.$800 per pregnancy.
Recognizing that most women in non-industrialized countries would not even have the opportunity to consider a drug regimen that must be taken throughout the last trimester because they have limited or no access to antenatal care, researchers set out to evaluate a more feasible course of therapy. They chose a shorter course of oral AZT administered throughout the last days of pregnancy and during labor and delivery--the time when most mother-to-child transmission appears to occur.
Trials of this short course of AZT, sponsored by the ministries of public health in Thailand and Côte d'Ivoire and the U.S. Centers for Disease Control and Prevention, began in 1996. This year, the results from Thailand showed that the shorter regimen reduced mother-to-child transmission by half.3
Both the reduced course of AZT and the HIV testing and counseling that must precede it are beyond the grasp of many HIV-infected pregnant women. But these results have triggered interest among governments and international donors in making this method of preventing maternal-child HIV transmission more widely available. The manufacturer of zidovudine, Glaxo Wellcome, recently agreed to reduce the price for women in low- and middle-income countries, and the Joint United Nations Programme on HIV/AIDS (UNAIDS) is working with governments to provide access to short-course AZT in 11 African, Asian and Latin American nations.
The cost of this therapy still poses a barrier for governments trying to expand access and for individuals who may try to buy it through private health care providers. The discounted price of U.S.$50 is many times the per capita health expenditure of most non-industrialized countries, and it does not include the additional cost of antenatal HIV counseling and testing and baseline laboratory tests. These costs raise questions of long-term sustainability after subsidies are reduced or eliminated.
Another critical question rarely mentioned in the debate or the research on AZT and maternal-child transmission is how to maintain the health and well-being of HIV-positive mothers. One of the many contradictions of preventing mother-to-child HIV transmission is that while short-course AZT decreases child mortality, it has no known impact on the health of the mother.
After short-course AZT treatment, HIV-positive mothers are still faced with the burden of their own infection and the likelihood that they will die from AIDS before their infants grow up. Preserving the health of HIV-positive mothers after they give birth should also become a priority, for their own sake and to ensure the continued survival of their infants.
Breast-feeding Dilemma
Providing short-course AZT therapy to breast-feeding mothers may not be effective because the infants who escaped HIV infection during pregnancy and delivery may become infected through breast milk. Up to one-third of all mother-to-child HIV transmission is due to breast-feeding.
For mothers in resource-constrained countries, this risk poses an agonizing dilemma. By choosing artificial feeding, a woman may avoid passing on HIV to her child. But where the water supply is unsafe, she may also expose her child to other deadly diseases. Research results suggest that in populations with high levels of infant mortality (usually due to infectious diseases), the risk of child death is actually lower if mothers with HIV breast-feed their infants.
Even when an HIV-positive woman knows she can bottle-feed her child safely, there are other disadvantages to artificial feeding. The most formidable obstacle is cost. For example, a year's supply of artificial milk for an infant will cost a Vietnamese family more than the country's per capita annual income. In addition, since prolonged breast-feeding has a naturally contraceptive effect, a woman who does not breast-feed may become pregnant again, repeating the dilemma. And if bottle-feeding becomes a badge of HIV status, a woman who decides not to breast-feed may risk loss of confidentiality and social rejection.
In the absence of clear guidance, mothers who know or suspect that they are HIV-positive must weigh the odds of infecting their babies with HIV, with its certain mortality, against risking infection and possibly infant death by feeding their babies formula mixed with water that may be contaminated.
Given the importance of breast-feeding for child health and the increasing prevalence of HIV infection around the world, health policymakers and service providers have struggled to develop appropriate and feasible guidelines on breast-feeding for HIV-positive mothers. This has proved to be extraordinarily difficult for a number of reasons.
First and foremost, most mothers do not know their HIV status. In non-industrialized countries, nine out of ten HIV-positive women are unaware that they are infected. Therefore, broader promotion of bottle-feeding could do more harm than good because it might encourage women who are HIV-negative to needlessly seek alternatives to breast-feeding.
On the other hand, more specific guidance is difficult because it is still not possible to compare the risk of HIV acquisition from breast-feeding with the risk of infant and child morbidity and mortality from unsafe artificial feeding in various settings. Researchers' attempts to determine these risks using mathematical models have been constrained by the limited information available, including a lack of consensus on the mechanisms and timing of HIV transmission through breast-feeding.
Early policy guidance to HIV-infected mothers in industrialized countries (where safe and affordable alternatives to breast milk usually exist and HIV counseling and testing are widely available) advised them to avoid breast-feeding. Consequently, very few HIV-positive mothers in these countries chose to breast-feed their children, and few children were infected from breast-feeding. At the same time, mothers in non-industrialized countries were being advised to continue breast-feeding.4
Recently, however, UNAIDS changed its guidelines from wholesale support of breastfeeding for HIV-positive mothers to supporting breast-feeding as the best method of feeding only for infants whose mothers are HIV-negative or whose mothers do not know their HIV status.5
The new guidelines emphasize the importance of supporting HIV-positive mothers in their right to choose an infant feeding method appropriate to their needs. They say that mothers who decide not to breast-feed must be ensured access to safe and sufficient quantities of nutritionally adequate breast milk substitutes-- a costly and problematic recommendation in many settings. They also call for improved access to antenatal services and voluntary, confidential HIV counseling and testing for pregnant women.
Without such services, women will not be able to make an informed choice about whether or not to breast-feed their children. Through counseling, both women and men of reproductive age can be informed of the implications of their HIV status for the health and welfare of their children. Women who are aware of their HIV-positive status need the best available information on the risk of HIV transmission through breast-feeding and on the risks and possible advantages of other methods of infant feeding. And women who are HIV-negative need to know that if they become infected after they begin breast-feeding, they are at heightened risk of passing on the virus in their breast milk because of the high concentrations of HIV in a person's blood early in infection.
Unanswered Questions
In the search for more effective and feasible ways of preventing mother-to-child transmission of HIV, many questions remain. Little is known about the interaction between short-course AZT treatment and breast-feeding, the potential of more affordable alternatives to AZT and bottle-feeding, or the impact of the fear of maternal-child transmission.
As efforts to expand access to short-course therapy begin, there is some concern that this drug regimen may actually increase the amount of HIV in a person's system during breast-feeding, reducing its efficacy in breast-feeding populations. This concern is based on observations of a rebound effect on viral load in some adults after they stop taking AZT and on the fact that short-course therapy ends just before breast-feeding begins.
Continuing AZT treatment during the breast-feeding period might reduce the risk of HIV transmission through breast milk, but no research has examined this question. If AZT was found to have a protective effect during breast-feeding, it would increase the rationale for countries to expand access to the drug for HIV-positive pregnant women. Otherwise, HIV transmission through breast-feeding will weaken the effect of AZT on child mortality.
Research is also needed to assess more affordable and feasible ways of preventing mother-to-child HIV transmission. For example, little is known about promising options for reducing the risk of HIV transmission through breast milk, such as adding Vitamin A to the diets of HIV-positive mothers and treating other maternal infections.
Even less is known about the psychological, sociological and possibly even immunological impact of the choices HIV-positive mothers must make. We do not know how the fear of infecting a young infant through breast-feeding-- a practice with deep cultural, emotional and psychological roots that is universal in many countries--affects women, families and society. We also do not know what toll the fear of infecting an unborn child takes on women and their families, particularly in cultures where children are highly valued and a woman's identity is closely associated with child-bearing. These fears may play a role not only in decisions about treatment or infant feeding, but also in HIV transmission itself.
Protecting Women and Children
Two interventions have been shown to reduce the risk of mother-to-child transmission: antiretroviral therapy for HIV-positive pregnant women and alternatives to breast-feeding. Another important--and often overlooked--option is primary prevention, or prevention of HIV in women of childbearing age.
The role of primary prevention in preventing HIV in children adds urgency to the need for policies and programs to reduce women's vulnerability to HIV. Practical measures to prevent HIV infection in women and men should include providing information about HIV/AIDS and its prevention, promoting safer sex and ensuring access to reproductive health services that include family planning and treatment for sexually transmitted infections.
It is encouraging that effective methods to limit mother-child transmission have been identified, but discouraging that, for the most part, they are too complicated and costly for universal use in the countries where they are most needed. Further research to answer the many unanswered questions and to develop simpler approaches is critical. Meanwhile, the most effective mechanism we have to prevent mother-to-child transmission remains prevention of the initial HIV infection in women.
-- Joan MacNeil
Joan MacNeil, PhD, is associate director of HIV/AIDS care and research in FHI's HIV/AIDS Prevention and Care Department in Arlington, Virginia.
References
- UNAIDS. 1998. Report on the global HIV/AIDS epidemic, June 1998. Geneva: World Health Organization.
- EM Connor, RS Sperling, R Gelber, et al. 1994. Reduction of maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine treatment. Pediatric AIDS Clinical Trials Group Protocol 076 Study Group. New England Journal of Medicine 331:1173-1180.
- Centers for Disease Control and Prevention. 1998. Administration of Zidovudine during pregnancy and delivery to prevent perinatal HIV transmission--Thailand, 1996-1998. Morbidity and Mortality Weekly Report 47(8):151-154.
- UNAIDS, WHO and UNICEF. 1997. HIV and infant feeding. A policy statement. Geneva: World Health Organization.
- UNAIDS, WHO and UNICEF. 1998. Consensus statement on infant feeding and HIV. Geneva: World Health Organization.
