Factbox: Five facts about U.S. Fed chair nominee Janet Yellen

(Reuters) - President Barack Obama will nominate Federal Reserve Vice Chair Janet Yellen to take the helm at the U.S. central bank when Ben Bernanke's term expires on January 31. A White House official said on Tuesday the announcement will be made at 3 p.m. (8:00 p.m. BST) on Wednesday. The nomination must be approved by the U.S. Senate. Following are five key facts about Yellen: - If confirmed by the Senate, Yellen, 67, would be first woman to head the U.S. Federal Reserve, and the second woman to lead a central bank for a developed nation. The first was Elvira Nabiullina, who was appointed to lead Russia's central bank in June. - She is seen as a dove on monetary policy, favouring strategies that bring down unemployment even at the risk of driving inflation higher. She has said she does not believe there is often conflict between the two Fed goals. "When the goals conflict and it comes to calling for tough trade-offs, to me, a wise and humane policy is occasionally to let inflation rise even when inflation is running above target," she said in 1995. - She has extensive policymaking experience. Before her appointment as Fed vice chair in 2010, Yellen took part in U.S. monetary policymaking as president of the San Francisco Federal Reserve Bank from 2004-2010, and as a governor on the Fed board from 1994 to 1997. She also chaired President Bill Clinton's Council of Economic Advisors from 1997 to 1999. - Yellen is a sharp and respected economist. With a PhD from Yale, she has taught economics at University of California, Berkeley, Harvard University and the London School of Economics, and she has published research on topics as disparate as youth gangs, single mothers, optimal monetary policy, wage and price rigidity, and trade. - Economics saturates her personal life as well. She is married to, and has co-authored a number of papers with, Nobel Prize-winning economist George Akerlof, whom she met in the fall of 1977 when they were both economists at the Fed board. They married the following June and left the Fed to teach at the London School of Economics. Their only child, now a university economics professor, knew he wanted to go into economics by the time he was 13. (Reporting by Ann Saphir; Editing by Grant McCool)