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April 27, 2005

Exclusive Breastfeeding Reduces Risk of Mother-to-Child HIV Transmission

Breastfeeding causes nearly 40 percent of all pediatric HIV infections, yet also prevents millions of child deaths every year by protecting infants from diarrhea and other infections. Finding ways to make breastfeeding safer for infants of HIV-infected mothers has been an urgent research priority. A study conducted by the Johns Hopkins Bloomberg School of Public Health, the University of Zimbabwe and Harare (Zimbabwe) City Health Department found that exclusive breastfeeding substantially reduces the transmission of HIV from mother to infant and infant death, compared with partial breastfeeding. Infants who were introduced to solid foods or animal milk within the first three months were at four times greater risk of contracting HIV through breastfeeding compared to those who were exclusively breastfed. The study is published in the April 29, 2005, issue of AIDS.

“International guidelines currently recommend that HIV-infected mothers should avoid all breastfeeding, but only if replacement feeding is acceptable, feasible, affordable, sustainable and safe,” said Jean Humphrey, ScD, principal investigator of the ZVITAMBO Study Project and associate professor with the Department of International Health at the Bloomberg School. “For the large majority of African women, this isn’t the case and breastfeeding is the only choice. Our findings indicate that for these mothers, delaying introduction of all non-breast milk foods will substantially reduce the risk of HIV and death for their infants.”

The study was conducted among 14,000 pairs of mothers and newborns who were part of the ZVITAMBO project, which examined the effects of vitamin A supplementation in Zimbabwe. From this group, the researchers followed 2,060 infants from birth to age 2 who were born to HIV-positive mothers. Information about infant feeding was collected at ages 6 weeks, 3 months and 6 months. All infants were breast fed, but were categorized as exclusive (breast milk only), predominant (breast milk and non-milk liquids) or mixed (breast milk and animal milk or solids) breastfeeding.

In their analysis, the researchers found that mixed breast feeding quadrupled mother-to-infant HIV transmission and was associated with a three times greater risk of transmission and death by age 6 months when compared to exclusive breast feeding. Predominant breastfeeding was associated with a 2.6-fold increase in HIV transmission as compared to exclusive breastfeeding.

“These findings suggest that early introduction of animal milk and solid food conveys especially high risk, but that even non-milk liquids like water or juice are likely to increase the risk of HIV transmission,” said Ellen Piwoz, ScD, a senior author of the paper, director of the Center for Nutrition at the Academy for Educational Development and adjunct assistant professor in the Department of International Health at the Bloomberg School. “Therefore, HIV-positive mothers who choose to breastfeed should do so exclusively, and the more strictly they are able to comply, the lower the risk of HIV or death will be for their infants.”

“Our findings underscore the importance of supporting exclusive breastfeeding, particularly in areas of high HIV prevalence where many women do not know their HIV status, and amongst HIV-positive mothers who choose to breastfeed. Early introduction of non-human milks and solid foods should be strongly discouraged because it increases the risk of HIV infection for babies of HIV-positive women and the risk of diarrhea and respiratory infections for all babies,” said Lawrence H. Moulton, PhD, the study’s senior statistician and professor in the Department of International Health at the Bloomberg School.

“Early exclusive breastfeeding reduces the risk of postnatal HIV-1 transmission and increases HIV-free survival” was written by Peter J. Iliff, Ellen G. Piwoz, Naume V. Tavengwa, Clare D. Zunguza, Edmore T. Marinda, Kusum J. Nathoo, Lawrence H. Moulton, Brian J. Ward, the ZVITAMBO study group and Jean H. Humphrey.

Funding was provided by the ZVITAMBO Study Project through grants by the Canadian International Development Agency, from the United States Agency for International Development through a cooperative agreement with Johns Hopkins University and through a grant from the Bill and Melinda Gates Foundation. Additional funding was provided by the Rockefeller Foundation and Support for Analysis and Research in Africa.

Public Affairs media contacts for the Johns Hopkins Bloomberg School of Public Health: Tim Parsons or Kenna Lowe at 410-955-6878 or paffairs@jhsph.edu.