The last two times Amazon has reported quarterly results, revenue fell short of expectations. Now, investors are facing the prospects of slowing growth at the e-commerce giant.

Amazon is scheduled to announce fourth-quarter earnings after the closing bell on Thursday. Analysts surveyed by Refinitiv expect the company to report revenue growth of 18.8 percent from a year earlier to $71.9 billion. That would mark the slowest fourth-quarter sales growth since 2014 and would be slightly below the top end of Amazon's guided range.

For a company of Amazon's size, that's still a big number. Amazon is expected to top $200 billion in full-year revenue for the first time. At $232.4 billion, analysts' average estimate, Amazon would be the sixth-largest U.S. company based on 2018 sales.

Here's what Wall Street is expecting for the quarter, according to Refinitiv consensus estimates:

EPS: $5.68 vs. $3.75 per share last year

Revenue: $71.9 billion vs. $60.5 billion last year

AWS: $7.3 billion (FactSet estimate) vs. $5.1 billion last year

In addition to the law of large numbers, there are several other reasons for the growth deceleration.

Amazon has been more focused on bolstering profitability than revenue in recent years, with growth coming from businesses like cloud, advertising and the third-party marketplace, where margins are bigger but sales are smaller. This is also the first time to get a fully comparable year-over-year number on Whole Foods, a slower-growing business.

Still, investors will be paying close attention to the top line. Since 2009, Amazon has only exceeded analyst expectations once in the fourth quarter.