WASHINGTON (AP) — Michelle Obama said Friday that it's wonderful that more of the world's girls are attending school, but advocates must counter the array of issues that force adolescent girls to drop out.

Among the issues are early or forced marriage, fear for the girls' physical safety as they travel to and from school, and economic disincentives, such as the cost of an education.

The first lady said the period when girls begin to develop from children into women "is when this issue truly starts to get hard." That is the time, she said, when they are first subjected to cultural values and practices "that define what it means to be a woman in her society."

In some countries, parents keep their daughters out of school because of fear that they will be attacked on the way there, an act that would be interpreted as harming the young woman's honor and ruining her future. In other instances, girls are kept home because the family can't pay for an education or can't afford the loss of household help.

Mrs. Obama argued that those reasons aren't good enough.

"Educating girls is one of the most powerful things that we can do not just for girls and their families, but for their communities and for their countries," she said in remarks to advocates who promote girls' education around the world.

The first lady, a mother of two teenage daughters, became more outspoken on the issue after more than 200 Nigerian schoolgirls were kidnapped by Islamic extremists earlier this year.

"We need parents to actually believe their daughters are as worthy of an education as their sons, and that sending girls to school is a good investment for their future," she said.

Mrs. Obama said 56 million more girls are attending school now than a decade ago, but 62 million girls still are not in school. And less than 10 percent of girls in some countries complete secondary school, she said.

The first lady told the advocates that "I'm in" on the issue, and that she will "use my voice, my platform" to help move it forward.

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