UPDATE 2-Centene raises 2018 outlook on growing Obamacare business

(Adds details on health benefits ratio, analyst comment, shares)

Feb 6 (Reuters) - Health insurer Centene Corp raised its full-year earnings forecast on Tuesday, helped by its growing Obamacare business and the recent changes to U.S. tax laws.

The company also reported a better-than-expected quarterly profit, beating analysts' estimates by 4 cents, as it signed up more people for its insurance plans.

Last month, the company said more than 1.4 million people had paid for its insurance plans via the federal Obamacare marketplace, as of Jan. 7.

Total membership was 12.2 million, as of Dec. 31, an increase of 765,300 members, or 7 percent, in 2016.

Health benefits ratio, or the amount it spends on medical claims compared with its income from premiums, increased to 87.3 percent in the fourth quarter from 84.8 percent a year earlier.

Centene raised its 2018 adjusted earnings forecast to $6.95-$7.35 per share from $5.47-$5.87 per share.

Analysts were expecting earnings of $6.11 per share, according to Thomson Reuters I/B/E/S.

Excluding items, the company earned 97 cents per share.

Total revenue rose 7.5 percent to $12.81 billion, ahead of analysts' expectations of $12.54 billion.

Piper Jaffray analyst Sarah James said the results were "largely positive," noting that the strong flu season won't likely repeat in 2018 and the company is progressing on bringing down medical costs.

The U.S. is currently facing a severe flu season, with hospitalizations at the highest in nearly 10 years, health officials said last week.

However, net earnings attributable fell to $230 million, or $1.30 per share, in the quarter ended Dec. 31, from $261 million, or $1.49 per share, a year earlier, partly due to higher expenses.

Centene's shares were down about 2 percent in light premarket trading. (Reporting by Ankur Banerjee in Bengaluru; Editing by Martina D'Couto)