At what age do stop breast feeding a baby?

7 years:

The anthropologically normal age to stop breastfeeding is round about age 7. Hence the phrase "milk teeth" and the fact that children start to loose their milk teeth at about that age. The average age of weaning from the breast worldwide is about 4 years; when you consider how many babies in western countries are weaned very, very early, that means an awful lot of children are breastfed for much longer than 4 years. The WHO advises breastfeeding for at least 2 years and for as long after that as necessary for the health and happiness of both mother and baby.