Concerns about China and other developing economies weakened the Australian dollar and currencies closely linked to commodities markets.
The ECB's forward guidance may adjust policy to tighten the slack in the Euro zone economy, a senior ECB official said.
The U.S. dollar was supported by hopes U.S. job growth would pick up in the wake of last week's data.
Unexpectedly strong non-farm payroll data boosted the dollar, despite the cold winter across much of the United States.
The euro added half a cent after the European Central Bank left interest rates unchanged.
The yen extended its losses against the dollar and euro as concerns over the standoff between Russia and Ukraine eased somewhat.
The dollar, ruble and euro rose against the yen on Tuesday, helped by signs Russia may want to avoid more military action in Ukraine.
Ukraine tension shakes investors, who head for the greenback on strong US spending data.
The dollar fell to a two-month low against the euro after data showed euro zone inflation unexpectedly held steady this month.
Fears over a Russian intervention in Ukraine and a Chinese slowdown sent traders to the Swiss franc and Japanese yen.
Putin's war games in Ukraine and a government report showing new housing sales at five-year highs both boosted the greenback on Wednesday.
The dollar fell against a basket of major currencies after soft U.S. consumer confidence data drove bond yields lower.
The dollar lost its safe haven bounce as risk appetite improved amid expectations that Ukraine would receive international aid.
U.S. data this week will continue to reflect the impact of extreme weather, presenting a downside risk for the U.S. dollar.
The National Association of Realtors delivered some bad news, sending the euro back up against the dollar.
A still fragile outlook for the European economy and strong US economic growth helped push the greenback up.
The dollar was steady ahead of Janet Yellen's testimony in Congress, while Norway's crown jetted almost 1 percent higher.
Global currency markets trod water ahead of interest rate decisions in Britain and the euro zone on Thursday.
The yen gained on Wednesday, as struggles in stock markets and the emerging markets forced investors to seek safe-haven currencies.
The Australian dollar surged almost two percent on Tuesday after moves from the country's central bank dropped.