Millions of girls worldwide are condemned to lives of hardship because they don't go to school, an education gap that entrenches broader extreme poverty, a new report said.
The report, "Because I am a Girl: The State of the World's Girls 2012," was released in New York by Plan International on the first International Day of the Girl organized by the United Nations.
"The estimated 75 million girls missing from classrooms across the world is a major violation of rights and a huge waste of young potential," the child poverty alleviation group said in launching the report.
A total of one in three girls is denied education, but Plan's report focuses especially on 39 million girls aged between 11 and 15, right on the cusp of becoming young women, who are out of school.
The report -- which came as a 14-year-old Pakistani girl was gunned down this week for her criticism of Taliban campaigns against girl's education -- underlined the hugely positive impact that school can have on girls in poor countries.
"An educated girl is less vulnerable to violence, less likely to marry and have children when still a child herself, and more likely to be literate and healthy into adulthood -- as are her own children," Plan International CEO Nigel Chapman said.
"Her earning power is increased and she is more likely to invest her income for the benefit of her family, community and country. It is not an exaggeration to say educating girls can save lives and transform futures."
In Washington, President Barack Obama's administration marked the inaugural Day of the Girl by pledging to promote "the rights and status of girls here in the United States and around the world."
"We know that when girls have access to education and health care, are safe from violence, and have equal opportunities to reach their full potential, families and communities are more likely to thrive," the White House said.
Plan called on global leaders to ensure a minimum of nine years' schooling for all children, giving them a better chance to enter secondary education.
But special priority should be given to girls, the humanitarian organization said, with greater funding and programs to stop child marriage and violence in schools -- two main reasons for the current dropout rate among girls.
In many cases, poor families pull daughters from school out of fear for their health or safety. In Ghana, 83 percent of parents interviewed for the report said the risks of pregnancy were a disadvantage of school.
The report said that in Togo, 16 percent of children interviewed named a teacher responsible for a classmate's pregnancy. That figure was 15 percent in Mali and 11 percent in Senegal.
In Ghana, 75 percent of children said teachers were the main source of school violence.
The opposite trend is also true, with school attendance leading to an ever-widening series of benefits.
"If adolescent girls stay in school and obtain real skills, research shows that they will earn more income in the future, marry later and have fewer and healthier children," Plan said. "In the longer term, secondary education protects girls against HIV and AIDS, sexual harassment and human trafficking."
US Secretary of State Hillary Clinton also spoke out on the first UN day for girls, saying the US government would expand efforts to keep girls in school and out of marriage around the world.
"Every year, 10 million girls under the age of 18 become child brides, and many of them under the age of 16," Clinton said. "Many of those girls are forced into early marriage, which robs them of the opportunity to continue their education, and it threatens their health, and it traps them in lives of poverty."
As the report came out, Pakistani teen Malala Yousafzai was fighting for her life after being shot in the head in broad daylight on a school bus.
Her struggle resonated with tens of thousands of girls denied an education by militants across northwestern Pakistan, where the government has been fighting local Taliban since 2007.