The report, "Because I am a Girl," said 2 million girls are subjected to genital mutilation and nearly 1 million are victimized by child traffickers, four times the number of boys who are victimized, the Independent reported.
The report from Plan International said girls are not as well educated as boys, and many suffer stunted growth due to poor nutrition.
"Why, in an era that saw the term 'girl power' coined, are millions of girls being condemned to a life of inequality and poverty?" the report asks.
"The study shows that our failure to make an equal, more just world has resulted in the most intolerable of situations. To discriminate on the basis of sex and gender is morally indefensible. It is economically, politically and socially unsupportable," Graca Machel, a children's rights campaigner from Mozambique, told the Independent.
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