Early Breast-feeding Recommended to Reduce Perinatal HIV Transmission

By Liz Highleyman

Exclusive early breast-feeding is associated with a lower rate of mother-to-child HIV transmission compared with mixed feeding in developing countries, and use of antiretroviral therapy may further reduce the risk, according to 2 recently published studies.

Currently, in developed countries where clean water and a reliable supply of safe infant formula can be assured, HIV positive women are advised not to breast-feed. However, in resource-limited settings, the World Health Organization (WHO) recommends breast-feeding, especially during the first 6 months, unless formula-feeding is acceptable, feasible, affordable, sustainable, and safe.

Exclusive Breast-feeding

As reported in the March 31, 2007 issue of The Lancet, researchers with the Africa Center for Health and Population Studies assessed the risk of HIV transmission and infant survival associated with exclusive breast-feeding and other types of infant feeding. This non-randomized intervention cohort study included 1372 HIV positive and 1345 HIV negative pregnant women attending prenatal clinics in KwaZulu Natal, South Africa. For 6 months, infant feeding data were obtained every week from the mothers (who kept feeding diaries) and blood samples from infants were drawn monthly to assess HIV infection status.

Results

• 83% of infants born to HIV positive mothers were exclusively breast-fed from birth, 8% received exclusive replacement feeding, and 3% started with a mix of breast-feeding plus other fluids or solid foods.

• For 1276 infants with complete feeding data, the median duration of exclusive breast-feeding was 159 days.

• 14.1% of exclusively breast-fed infants were infected with HIV by 6 weeks of age, and 19.5% by 6 months.

• The estimated risk of HIV infection at 6 months of age was 4.04%.

• Breast-fed infants who received solid foods in addition to breast milk were significantly more likely to acquire HIV than exclusively breast-fed babies (HR 10.87), as were infants who received both breast milk and formula (HR 1.82).

• The cumulative 3-month mortality among exclusively breast-fed infants was 6.1%, compared with 15.1% for infants who received breast milk plus solid foods or formula (HR 2.06).

• The risk on infant HIV infection was significantly associated with maternal CD4 cell count below 200 cells/mm3 (HR 3.79) and birth weight less than 2500 g (HR 1.81).

Based on these findings, the authors concluded, "The association between mixed breast-feeding and increased HIV transmission risk, together with evidence that exclusive breast-feeding can be successfully supported in HIV-infected women, warrant revision of the present UNICEF, WHO, and UNAIDS infant feeding guidelines."
Accumulating evidence - such as that provided by a recent outbreak of diarrhea among formula-fed infants in Botswana "Formula-feeding Linked to Infant Diarrhea Outbreak in Botswana" - suggests that for HIV positive women in developing countries, the benefits of breast-feeding may outweigh the risk of HIV transmission (about 1% per month). Furthermore, studies reported at the recent 14th Conference on Retroviruses and Opportunistic Infections showed that early weaning before 6 months was not associated with a decreased risk of HIV transmission compared with continued breast-feeding.

Antiretroviral Therapy

The authors of the South African study suggested that "initiation of [antiretroviral] treatment should be an overriding priority" for HIV positive pregnant women.

This recommendation is supported by another recent study reported in the March 1, 2007 Journal of Acquired Immune Deficiency Syndromes. Italian researchers assessed the effect of antiretroviral treatment on breast milk viral load and determined plasma and breast milk drug concentrations in pregnant women taking part in the Drug Resource Enhancement Against AIDS and Malnutrition (DREAM) program in Mozambique.

The study included 40 women receiving combination therapy with AZT (zidovudine; Retrovir), 3TC (lamivudine; Epivir), and nevirapine (Viramune) from 28 weeks of gestation to 1 month postpartum, and 40 untreated pregnant women. Infants received a single dose of nevirapine within 72 hours of birth; mothers agreed not to breast-feed and were provided free formula.

Results

• Women in the treated group received a median of 85 days of therapy before delivery.

• At delivery, the median plasma viral load was 2.2 log in the treated group compared with 4.8 log in the untreated group.

• At delivery, in the treated group, the median viral load was higher in breast milk than plasma (2.3 vs 2.2 log), while the reverse was true in the untreated group (3.4 vs 4.8 log).

• By day 7, median breast milk viral loads were lower than plasma HIV RNA levels in both groups.

• HIV RNA levels in breast milk were significantly lower in the treated group compared with the untreated group:

- At delivery: median 2.3 vs 3.4 log (P < 0.001);
- 7 days post-partum: 1.9 vs 3.6 log (P < 0.001).

• Among women with detectable viral loads at delivery, median breast milk concentrations of nevirapine, AZT, and 3TC were 0.6, 1.1, 1.8, and 1.1 times higher than maternal plasma concentrations, respectively.

• 10% of women had detectable nevirapine in breast milk but not in plasma, suggesting the drug may be eliminated more slowly from breast milk.

"Antiretroviral drugs administered during the last trimester of pregnancy and after delivery reach levels similar to or higher than plasma concentrations in breast milk and can significantly reduce HIV RNA levels," the authors concluded. "Our data support the potential role of maternal HAART prophylaxis in reducing the risk of breast-feeding-associated transmission."

04/10/07

References

HM Coovadia, NC Rollins, RM Bland, and others. Mother-to-child transmission of HIV-1 infection during exclusive breastfeeding in the first 6 months of life: an intervention cohort study. Lancet 369(9567): 1107-1116. March 31, 2007.

M Giuliano, G Guidotti, M Andreotti, and others. Triple Antiretroviral Prophylaxis Administered During Pregnancy and After Delivery Significantly Reduces Breast Milk Viral Load: A Study Within the Drug Resource Enhancement Against AIDS and Malnutrition Program. JAIDS 44(3): 286-291. March 1, 2007.