A malnourished child sleeps inside a ward at Assabiyn hospital in Sanaa February 11, 2012. Political turmoil has pushed Yemen, already one of the poorest countries in the Arab world, to the brink of a humanitarian crisis to rival the one that ravaged the Horn of Africa last year.The United Nations Children's Fund, UNICEF, says 57 percent of Yemen's 12 million children are chronically malnourished -- the highest level of chronic malnutrition in the world after Afghanistan. Picture taken February 11, 2012. To match Feature YEMEN-CHILDREN/ REUTERS/Khaled Abdullah (YEMEN - Tags: SOCIETY POVERTY HEALTH)