WellPoint Inc.’s first-quarter profit improved modestly, but soared above the expectations of Wall Street analysts.

The Indianapolis-based health insurer responded by boosting its full-year profit forecast by 40 cents per share.

WellPoint earned $926.6 million, or $2.44 per share, in the three months ended March 31. That marks a 5.7 percent increase in profit over the same quarter last year.

Excluding investment gains and special items, WellPoint’s profit rose 2.2 percent to $891 million, or $2.35 per share.

On that basis, analysts were expecting $1.87 per share, according to a survey by Thomson Reuters. A year ago, WellPoint earned $1.95 per share, excluding special charges.

Much of the per-share profit increase is due to WellPoint’s share repurchase program, which reduced its shares outstanding by 15 percent in the past year.

Revenue for the quarter fell 1.2 percent compared to a year ago, to $14.9 billion.

“Our membership and earnings results are higher than we originally anticipated and we are continuing to become a more efficient and effective company,”  WellPoint CEO Angela Braly said in a statement.

Indeed, WellPoint added 875,000 new members to its health plans in the first quarter, seeing growth across all business lines except individual policies.

The company had 34.2 million members on March 31, and now predicts it will hold on to more of them during the year, finishing 2011 with 33.9 million members.

For the year, WellPoint now expects earnings per share of $6.70, compared with a February forecast of $6.30 per share.