One in five children in rich countries lives in relative poverty, according to a UNICEF report published yesterday that put the U.S. and New Zealand among the world's worst performers for youth well-being. Nearly 13 percent of children in those countries lack access to sufficient safe and nutritious food, the report said, with that number rising to 20 percent in the US and UK.

"Higher incomes do not automatically lead to improved outcomes for all children, and may indeed deepen inequalities," said Sarah Cook, director of the UNICEF Innocenti research office that published the study. "Governments in all countries need to take action to ensure the gaps are reduced and progress is made," she said.

The 'Report Card' took into account factors like education, mental health, alcohol abuse, economic opportunities and the environment to rank 41 high-income countries for overall youth well-being. Germany and the Nordic countries topped the list while Romania, Bulgaria and Chile came in at the bottom, with New Zealand and the U.S. in 34th and 37th place respectively. The U.S. had relatively low scores in terms of poverty, hunger, health, education and inequality. The number of adolescents reporting mental health problems is increasing in the majority of the countries included in the study, along with the rate of obesity among young people.