Despite growing evidence the global economy is faring better than it has for years, Christine Lagarde said policymakers around the world have to be alert to the potential repercussions from the Fed's "tapering," a policy change it decided to embark upon in December.

So far, the move has been minimal - it has reduced the amount of bonds it buys each month by $10 billion to $75 billion - but many economists think that it could end this year if the U.S. economic recovery gains steam.