Washington: US President Barack Obama called himself a feminist in an essay published on Thursday in Glamour magazine, urging all men to keep fighting against gender stereotypes and double standards. Thursday is Obama's 55th birthday and also the last one he can celebrate in the White House. In the essay titled "This is What a Feminist Looks Like," he writes: "It's important that their (his two daughters') dad is a feminist, because now that's what they expect of all men." He is reportedly the first sitting US president to openly proclaim that he is a feminist. The 1500-word essay was widely praised in social media here. Reviewing what have shaped his own feminism, Obama cited the hardworking of his mother and grandmother and the pressure on his wife Michelle to balance her career and parenting. However, he weighed watching his daughters grow up as the strongest factor in shaping his thoughts about feminism. "When you're the father of two daughters, you become even more aware of how gender stereotypes pervade our society," he says. "You see the subtle and not-so-subtle social cues transmitted through culture. You feel the enormous pressure girls are under to look and behave and even think a certain way." "While I'll keep working on good policies - from equal pay for equal work to protecting reproductive rights - there are some changes that have nothing to do with passing new laws," he wrote. "In fact, the most important change may be the toughest of all - and that's changing ourselves." "Michelle and I have raised our daughters to speak up when they see a double standard or feel unfairly judged based on their gender or race - or when they notice that happening to someone else," he said. The US president has called for all men join him to keep fighting gender discrimination and changing attitudes which limit girls' development by boxing stereotypes on gender behaviors since they are young, stressing the importance for girls "to see role models out in the world who climb to the highest levels of whatever field they choose." "It is absolutely men's responsibility to fight sexism too. And as spouses and partners and boyfriends, we need to work hard and be deliberate about creating truly equal relationships," he said in the essay. "That' s what twenty-first century feminism is about: the idea that when everybody is equal, we are all more free." Obama attaches importance to feminism at a critical time when Democratic presidential candidate Hillary Clinton is closer to the White House than any woman before her and nearly a century after women's suffrage in the country. "No matter your political views, this is a historic moment for America. And it's just one more example of how far women have come on the long journey toward equality," he said.