At the start of World Breastfeeding Week Monday, UNICEF said breastfeeding was most important in the first two years of life, including exclusive breastfeeding in the first six months.
Infants who are not adequately breastfed are left with limited defenses against fatal diseases like pneumonia and diarrhea and lack essential nutrients to develop body and mind.
Currently, an estimated 63 per cent of children less than six months old in the developing world are not breastfed adequately in the critical period if at all, the U.N. agency said.
"Exclusive breastfeeding is ideal nourishment for babies up to six months old," said UNICEF Executive Director Ann Veneman. "In a developing country, a child that is not breastfed is about three times more likely to die in early infancy than a breastfed child, and exclusive breastfeeding reduces the risk still further."