Shares supplemental health insurance provider Aflac, Inc. rose on Wednesday(NYSE: AFL) as the company posted first quarter earnings that exceeded estimates, as strong U.S. sales offset its declining Japan sales.

The Columbus, Ga.-based company reported late Tuesday that it earned $416 million, or 84 cents per share in its first quarter, up 11 percent from the same period a year ago. Analysts polled by Thomson Financial expected earnings of 79 cents per share.

Shares of Aflac rose $2.23, or 4.53 percent, to close at $51.45 on the New York Stock Exchange.

Aflac said operating earnings, one of its key measures of profitability, rose 13.9 percent to $407 million, or 82 cents per share. The figure includes impact from a weaker yen but excludes investments.

Overall, revenue rose 5.4 percent to $3.75 billion, from $3.56 billion in the same quarter last year. US performance helped offset a lag in its much larger Japan operations where the firm makes nearly three quarters of its revenue.

The firm's U.S. premium income increased 10.9 percent to $961 million. Net investment income rose 10.3 percent to $122 million, helping drive up total revenue 10.7 percent to $1.1 billion.

Total Japan sales fell 10.6 percent to $221 million in the first quarter.

Despite a challenging Japanese sales market, Aflac Chairman and CEO Daniel Amos remained upbeat in a statement released on Tuesday.

Our persistency remained strong and despite a sales decline, Aflac Japan's annualized premiums in force still rose 4.8 percent, he said. At the same time, our benefit ratio again improved, and our expense ratio remained stable, resulting in improved profitability.