WASHINGTON, D.C. - Because HIV can be transmitted through breast milk, to breast-feed or not to breast-feed has become a thorny issue among pediatricians involved in AIDS prevention.
According to World Health Organization (WHO) officials, the critical element in reducing HIV transmission from mother to infant in developing countries has been the role of breast-feeding. In industrialized countries, for example, the benefits of antiretroviral agents such as zidovudine (AZT, Retrovir, Glaxo Wellcome) in reducing perinatal transmission can be diminished when the infected mother begins breast-feeding. But women in developing countries have to choose between offsetting the risk of transmitting HIV through their breast milk vs. the benefits of breast-feeding their child, which in the developing world is critical to the future health of the infant.
One South African study looked at the impact of breast-feeding on the growth morbidity and mortality in infants of mothers with HIV. Pediatricians followed the infants from birth and at each visit examined their growth and feeding methods and recorded any current or past illness, regardless of severity.
Two groups consisting of 90 non-infected infants and 43 infected infants were enlisted in the study. Thirty-six of the infants were exclusively breast-fed, 76 received mixed feedings of formula and breast milk, and 21 were fed only infant formula.
The HIV transmission rate from mother to newborn was 39% in those exclusively breast-fed, 24% in those using formula alone, and 32% in those receiving both breast milk and formula. There was also an increase in HIV transmission from mother to infant over the first three months for breast-fed infants, as well as a higher mortality rate of 19% compared with 13% for breast- and bottle-fed infants.
The researchers could find no difference among the three groups regarding growth retardation or frequencies of diarrhea and pneumonia. The study appeared to indicate that breast-feeding by HIV-infected women seemed to actually delay the onset of AIDS in their infants, but failed to protect them against other common childhood illnesses.
These findings should be incorporated into counseling in developing countries so women can make informed decisions about breast-feeding, said the researchers.
In an ongoing case study of children born to mothers with HIV, Argentinean researchers found an increased risk in infants who were breast-fed by HIV-infected mothers and later became infected.
Scientists tracked the progress of an infant born to a seronegative mother and seropositive father. The mother was under the care of doctors while she was pregnant and after the baby was delivered vaginally.
The mother and child tested negative at delivery and at 10 months postpartum. The infant's development was normal without any of the complications normally associated with HIV infection until the age of 10 months. But the child returned to the clinic at 32 months showing generalized lymphadenopathy and a right parotitis. Both mother and child were HIV positive by Western blot.
Since the mother had breast-fed the child up to the age of 24 months, the Argentinean researchers believe that she had been infected and seroconverted between her child's 10th and 23rd month and then transmitted the virus to him while breast-feeding.
"We know that the virus can be found in the mother's breast milk, that it can be found through DNA and RNA PCR tests which indicate that both cell-free and cell-associated virus is present," said Maria Avila, MD, clinical researcher for the national Reference Center for AIDS in Buenos Aires and one of the study's authors. "The association between viral loads in breast milk and transmission to the infant has not been clearly defined yet, but the longer one breast-feeds, the greater the risk of transmission."
Researchers out of Sao Paulo State, Brazil, found that breast-feeding increased the risk of HIV-1 transmission independent of its duration or maternal HIV disease. They looked at the relationships between breast-feeding and the mother's socioeconomic, behavioral and obstetrical factors and the reasons behind why the mothers breast-fed.
The study covered HIV-infected women and their children born between January 1988 through April 1993. Data on maternal, obstetrical, neonatal and postnatal factors were collected from medical records and questionnaires. Pediatric infection was determined by antibody tests at 18 months of age or by AIDS diagnosis at any age.
Of the 434 children tested, 69 were found to have been infected but 19 were infected through breast milk. Breast-fed children had a higher risk than those who were bottle-fed, and this association became stronger after controlling for advanced maternal HIV disease.
The mean duration of breast-feeding was 98 days; the median 30 days. No clear trend was observed with duration. The attributable risk of infection for breast-feeding was 8%; the total attributable risk including breast-feeding was 19%.
Women who breast-fed were significantly more likely to be non-white, HIV asymptomatic, or have delivered in 1988 or 1989. Breast-feeding was not associated with other maternal factors (age, mode of HIV infection, drug use during pregnancy), obstetrical factors (mode of delivery, length of gestation) or socioeconomic factors (income, household plumbing, work outside home, education, antenatal care).
The reasons for breast-feeding were: women
Pregnant women should be offered HIV testing antenatally. Infected women should be counseled about the risks of breast-feeding before delivery and alternatives for breast milk should be provided for women who cannot afford formula feeding.
For more information:
- Coovadia H, Bobat R. Decreased protectiveness and increased virus transmissibility of breast milk from HIV-infected mothers: implications for national breast-feeding policy. Presented at the Conference on Global Strategies for the Prevention of HIV Transmission from Mothers to Infants. Sept. 3-6. Washington, DC.
- Tess BH. Breast-feeding among HIV-infected women in Sao Paulo State, Brazil. Presented at the Conference on Global Strategies for the Prevention of HIV Transmission from Mothers to Infants. Sept. 3-6. Washington, DC.
- Avila MM. HIV-1 transmission through breast-feeding in Argentina. Presented at the Conference on Global Strategies for the Prevention of HIV Transmission from Mothers to Infants. Sept. 3-6. Washington, DC.
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