April 24 (Bloomberg) — Aetna Inc., the third-largest carrier, reported profit that beat analyst estimates and raised its forecast as membership rose for the eighth consecutive quarter.

First-quarter earnings excluding one-time items were $1.98 a share, 43 cents above the average of 16 analysts' estimates compiled by Bloomberg. Aetna raised its full-year earnings forecast to $6.35 to $6.55 a share, according to a company statement today. The insurer's previous outlook was for at least $6.25.

Medical membership rose to more than 22.7 million in the quarter, an increase of 529,000 members from the beginning of the year, the Hartford, Connecticut-based company said. Bad winter weather and a mild flu season helped keep costs down as patients stayed away from the doctor, offsetting the cost of new expensive drugs, including Gilead Sciences Inc.'s $1,000-a-pill hepatitis C treatment.