UnitedHealth Group (NYSE: UNH) is scheduled to release its quarterly earnings report tomorrow, and the company is at the epicenter of the debate over health care reform and the gradual implementation of Obamacare. But with the stock trading near all-time highs, will UnitedHealth be able to overcome the impediments that Obamacare has put in its path and produce the earnings growth investors want to see?

As the newest member of the Dow Jones Industrials (INDEX: ^DJI), UnitedHealth is a giant in the health care industry. The prospect of bringing millions of previously uninsured Americans onto its insurance rolls has helped push UnitedHealth stock to all-time highs recently, but analysts are less certain that UnitedHealth's earnings will grow as quickly. Let's take an early look at what's been happening with UnitedHealth over the past quarter and what we're likely to see in its quarterly report.

Stats on UnitedHealth

Analyst EPS Estimate

$1.25

Change From Year-Ago EPS

(1.6%)

Revenue Estimate

$30.5 billion

Change From Year-Ago Revenue

11.9%

Earnings Beats in Past 4 Quarters

3

Source: Yahoo! Finance.

Where will growth in UnitedHealth earnings come from?
UnitedHealth's earnings prospects have gotten drearier in the eyes of analysts in recent months: Estimates for the June quarter have come down by a nickel per share, and estimates for the 2013 and 2014 years have been lowered even more. The stock, though, has put in some decent gains, rising about 7% since mid-April.

Already, investors have prepared for what they see as an inevitable slowdown in UnitedHealth's earnings growth. Even as earnings have grown about 15% annually over the past five years, UnitedHealth sees that growth rate falling into the single digits this year and next. Yet while the stock's earnings multiple of about 13 doesn't look ridiculously overpriced, UnitedHealth's valuation is far greater than the single-digit P/Es that Humana (NYSE: HUM) and WellPoint (NYSE: WLP) sport, despite all three companies' sharing the same opportunity to pick up millions of new customers once Obamacare fully takes effect. Moreover, with doubts arising about whether state-run health exchanges will be lucrative enough to justify participating in, it's far from clear whether UnitedHealth, Humana, WellPoint, and other insurers will choose to offer insurance in many jurisdictions.

But UnitedHealth has some lucrative business opportunities beyond simple health insurance. Its Optum subsidiary stands to be instrumental in managing health-benefits data, helping businesses manage health care information and coordinate it with the benefits they offer to ensure smooth operation of their health programs. With all the changes Obamacare will bring, investors can expect Optum's services to become increasingly important not only for UnitedHealth but for businesses across the country seeking to comply with the law.

More interesting is UnitedHealth's recent investment in Brazilian insurer Amil. By looking abroad, UnitedHealth is taking the opportunity to diversify its political exposure, leaving itself with an out even if Obamacare proves to be disastrous to its business model. With UnitedHealth having begun a tender offer in March to take over the 30% of Amil's shares that public investors own, the company should be in a position to start broadening its international empire and become a worldwide health-insurance leader in the long run.

In UnitedHealth's earnings report, watch closely for further updates on the company's revenue expectations for the year. Last quarter, UnitedHealth cut its projections by $1 billion to $2 billion, sending shares down sharply. If the insurer has to report another cut in guidance, then UnitedHealth's recent stock gains could evaporate quickly.

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Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter @DanCaplinger. The Motley Fool recommends UnitedHealth Group and WellPoint. The Motley Fool owns shares of WellPoint. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.