US drug group Pfizer reported lower first quarter revenue and income as speculation swirled about its contentious bid for British rival Astrazeneca.Pfizer said the loss of exclusivity on some products and the end of joint promotions had led to a 9% fall in reported revenue to a lower-than-expected $11.4bn and a 2% dip in adjusted income to $3.7bn.The company, however, confirmed adjusted expectations for the rest of the year "given the strength of our mid- and late-stage pipeline, the continued growth opportunities for our recently launched products as well as opportunities for upcoming product launches."It also said it continued to expect to repurchase about $5bn of its shares this year, with $1.7bn re-purchased to May 2nd. "These repurchases and planned repurchases will more than offset the potential dilution related to employee compensation programmes," it said.There has been speculation that Pfizer could table a revised bid for rival Astrazeneca or take its £63bn offer directly to the UK company's shareholders after Astrazeneca rejected the offer last week.Pfizer is considering spinning out its global established pharmaceuticals (GEP) division, which holds drugs whose patents have expired, or are about to, from its other potentially more lucrative units, according to the Lex column in the Financial Times.That casts question marks over which parts of AstraZeneca would be put into GEP and how costs would be allocated, should Pfizer succeed in its bid for the UK company.Uncertainty also surrounds the bid, with Astrazeneca urging the British government to remain neutral in its approach despite accusations that the Tory-led coalition government is backing a merger.The leader of the opposition Labour Party, Ed Miliband, has called for the bosses of both companies to appear before a parliamentary committee to explain how Pfizer would protect Astrazeneca's research and development operations in the UK.Pfizer has said it would press ahead with Astrazeneca's plans for a new R&D centre at Cambridge and would keep "substantial" activity at a factory in Macclesfield near Manchester. It has also said it would aim for a fifth of the company's combined staff to be based in the UK. Astrazeneca employs 6,700 people in Britain.Shares in Astrazeneca fell 65.5p, or 1.4%, to 4742.5p at 09:35 in London.PW