BENGALURU (Reuters) -India's Tech Mahindra on Wednesday posted a surprise 39% drop in first-quarter profit, as challenging macroeconomic conditions prompted clients to curb spending. Indian information technology (IT) companies have seen clients tighten spending amid fears of a recession in key markets U.S and Europe, resulting in subdued results for the quarter and warnings of slower revenue growth for the year. India's top two IT firms, Tata Consultancy Services and Infosys have warned of an uncertain demand environment, with the latter halving its full year revenue growth outlook.