Shares in French pharma group Sanofi bucked the trend, dropping 5.3 percent and adding to the previous session's slump, after its board said on Wednesday it had decided to oust chief executive Chris Viehbacher.
At 0807 GMT, the FTSEurofirst 300 index of top European shares was up 0.4 percent at 1,321.69 points, led by mining shares such as Rio Tinto and BHP Billiton up 0.9-1.2 percent, climbing along with metal prices.
The Fed is expected to announce the end of its bond-buying stimulus while restating its willingness to wait before hiking interest rates, which should reassure markets.