Early Exclusive Breastfeeding Significantly Reduces the Risk of HIV Transmission and Increases HIV-free Survival of Infants

The promotion of exclusive breastfeeding (EBF) to reduce the postnatal transmission (PNT) of HIV is based on limited data. In the context of a trial of postpartum vitamin A supplementation, researchers provided education and counseling about infant feeding and HIV, prospectively collected information on infant feeding practices, and measured associated infant infections and deaths.

A total of 14,110 mother-newborn pairs were enrolled, randomly assigned to vitamin A treatment group after delivery, and followed for 2 years. At baseline, 6 weeks and 3 months, mothers were asked whether they were still breastfeeding, and whether any of 22 liquids or foods had been given to the infant.

Breastfed infants were classified as exclusive, predominant, or mixed breastfed.

Results

· A total of 4495 mothers tested HIV positive at baseline;

· 2060 of their babies were alive, polymerase chain reaction negative at 6 weeks, and provided complete feeding information.

· All infants initiated breastfeeding;

· Overall PNT (defined by a positive HIV test after the 6-week negative test) was 12.1%, 68.2% of which occurred after 6 months;

· Compared with EBF, early mixed breastfeeding was associated with a 4.03, 3.79, and 2.60  greater risk of PNT at 6, 12, and 18 months, respectively; and

· Predominant breastfeeding was associated with a 2.63, 2.69 and 1.61 trend towards greater PNT risk at 6, 12, and 18 months, compared with EBF.

Based on these findings, the authors conclude, “Exclusive breastfeeding may substantially reduce breastfeeding-associated HIV transmission.”

Discussion

The findings of this study have three specific programmatic implications, according to the authors. First, the introduction before the age of 3 months of solid foods or animal milks to breastfeeding infants born to HIV-positive mothers was associated with a fourfold greater risk of PNT at 6 months compared with EBF.

The protective effects of early EBF were still significant at 18 months post-delivery, with a 61% reduction in PNT compared with MBF. The risk of PBF over EBF varied from 1.6 to 2.7 over the 18-month period, reaching statistical significance at 12 months only.

These findings indicate that the early introduction of non-human milks and solid foods conveys an especially high risk, but that even non-milk liquids are likely to increase the risk. Therefore, the more strictly HIV-positive mothers are able to breastfeed exclusively, the lower the risks of HIV or death will be for their infants.

Second, consistent with studies in West Africa, South Africa, and Tanzania, more than two-thirds of all PNT occurred after 6 months. Together, such studies provided strong justification for supporting early breastfeeding cessation among HIV-positive women. This can only be done, however, when women are socially supported to do so, and when safe nutritionally adequate alternatives are available.

Third, women with CD4 cell counts less than 200 cells/microliter were five times more likely to transmit HIV during breastfeeding compared with women with CD4 cell counts over 500 cells/microliter, confirming the findings of other studies that PNT is highly correlated with immune suppression.

Screening mothers for CD4 cell counts could help to identify infants at highest risk of PNT so that alternative feeding methods (or antiretroviral therapy for the mother) can be considered.

04/11/05

Reference
P J Iliff and others (the ZVITAMBO study group). Early exclusive breastfeeding reduces the risk of postnatal HIV-1 transmission and increases HIV-free survival. AIDS 19(7): 699-708. April 29, 2005.

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