April 15 (Reuters) - Advertising firm Omnicom Group OMC.N missed Wall Street estimates for first-quarter revenue on Tuesday, as an uncertain economic environment weighed on several of its segments, sending its shares down 3.6% in trading after the bell.

Omnicom witnessed declines in revenue growth across segments including healthcare, public relations, branding and retail, in the quarter, countering a 7.2% rise in the media and advertising business, the company's biggest.

The New York-based company, which competes with UK's WPP WPP.L, is one of the world's biggest integrated advertising and communications firms.

As businesses rein in ad budgets amid geopolitical tensions and stubborn inflation, the slowdown in client spending is weighing on revenue growth for major advertising firms like Omnicom.

Omnicom's revenue stood at $3.69 billion in the quarter ended March 31, compared with analysts' average estimate of $3.72 billion, according to data compiled by LSEG.

"We are assessing the implications of economic and market events to determine how they will affect our clients and business for the remainder of 2025," CEO John Wren said in a statement.

The company expects to close its acquisition of Interpublic Group of Companies IPG.N in the second half of the year, and sees the deal driving revenue growth and cost synergies.

On an adjusted basis, it earned $1.7 per share, compared with expectations of $1.62.

(Reporting by Priyanka.G in Bengaluru; Editing by Maju Samuel)

((Priyanka.G@thomsonreuters.com;))