The risk of HIV transmission from mother to child may be heightened in some developing countries because of difficulties some mothers have in adhering to infant feeding guidelines, according to research published in the journal AIDS.

The study reported that only 13 percent of women were able to adhere to exclusive breastfeeding and only 29 percent to exclusive formula feeding.

To reduce transmission risk, WHO/UNICEF guidelines state that breastfeeding should be avoided where there is access to affordable, sustainable and safe replacement formula. But in some countries, where resources such as running water are scarce, it is difficult for mothers to effectively implement these recommendations.

Recent studies have also shown that babies of HIV-positive mothers who both breastfeed and drink formula are almost twice as likely to become infected as children who breastfeed exclusively.