Famine has been formally declared in South Sudan and children in Nigeria, Somalia and Yemen are suffering from severe acute malnutrition.
The World Food Programme says 20 million lives are at risk in the next six months.
In northeast Nigeria, the number of children with severe acute malnutrition is expected to reach 450,000 this year, said the charity Unicef.
In Somalia, 185,000 children are already on the brink of famine. This figure is expected to rise to 270,000 in the next few months.
The UN estimates 6.2 million people in Somalia, half the population, are in need of humanitarian assistance.
In South Sudan, over 270,000 children are severely malnourished. And in Yemen, where a conflict has been raging for two years, 462,000 children are suffering from severe acute malnutrition – a near 200% increase since 2014.
