Vitamin A deficiency is estimated to affect approximately one third of children under the age of five around the world.[31] It is estimated to claim the lives of 670,000 children under five annually.[32] Approximately 250,000–500,000 children in developing countries become blind each year owing to vitamin A deficiency, with the highest prevalence in Southeast Asia and Africa.[33] Vitamin A deficiency is "the leading cause of preventable childhood blindness," according to UNICEF.[34][35] It also increases the risk of death from common childhood conditions such as diarrhea. UNICEF regards addressing vitamin A deficiency as critical to reducing child mortality, the fourth of the United Nations' Millennium Development Goals.[34]