March 1 (Reuters) - Shares in UBM Plc fall as much as 6 percent, after the company says it expects subdued performance in the first quarter and that growth at its events business in emerging markets will pick up in the second half of the year. UBM, which organises exhibitions, trade shows and conferences, says full-year adjusted pretax profit from continuing operations increases marginally to 151.8 million pounds in the year ended Dec. 31. Revenue rises 2 percent to 797.8 million pounds.