Corrects percentage change to 18 percent in first paragraph

Lockheed Martin Corp posted an 18 percent drop in first-quarter profit on Wednesday and lowered its full-year outlook, citing a charge tied to recent U.S. healthcare reform.

The world's biggest defense contractor said net earnings fell to $547 million, or $1.45 a share, from $666 million, or $1.68 a share, a year earlier.

The results include a charge of about 25 cents a share resulting from the new health reform law's elimination of tax deductions that have been available to companies for retiree prescription drug expenses.

Revenue rose about 3 percent to $10.64 billion, compared with $10.62 billion expected by analysts, according to Thomson Reuters I/B/E/S.

(Reporting by Karen Jacobs; Editing by Lisa Von Ahn)