Amazon.com Inc. is poised to report strong first-quarter earnings April 29. Analysts say this will provide an early glimpse into the e-commerce company's outlook in 2021 as the U.S. economy reopens after a major slowdown caused by the pandemic.

Analysts expect the Seattle company's first-quarter revenue to grow nearly 39% year over year to $104.65 billion, on the higher end of Amazon's guidance, according to S&P Capital IQ estimates as of April 26. Amazon previously said it expects first-quarter net sales of between $100 billion and $106 billion, representing between 33% and 40% year-over-year growth.

Analysts are also bullish on the company's profits. The consensus estimate for Amazon's first-quarter GAAP net income is $4.98 billion, or nearly twice the $2.54 billion Amazon reported in the first quarter of 2020.

Any uptick in earnings would come on top of two years of quarterly growth for Amazon, whose sales benefited during the pandemic as government lockdowns forced millions of consumers to stay home beginning in the spring of 2020. Amazon's revenue spiked 40.2% to $88.91 billion in the second quarter of 2020 on elevated customer demand that began in early March. The company's fourth-quarter 2020 sales reached $125.56 billion, up 43.6% from the year-ago quarter, thanks to holiday season gains that included Amazon's delayed two-day Prime Day event.

Cindy Liu, director of forecasting at eMarketer, said factors likely to have boosted Amazon's first-quarter sales include consumer spending of U.S. stimulus checks as well as growing confidence that the pandemic will wane as vaccines roll out. "If Amazon blows it out of the water in Q1, it might be a good indication that consumers are feeling more optimistic," Liu said.

Strong first-quarter earnings would reinforce Amazon as the No. 1 player in the U.S. e-commerce market, where it holds a commanding 40.41% share. Brick-and-mortar rival Walmart Inc. is a distant second with 7.11% of the market, according to eMarketer.

Daniel Sparks, a contributing senior technology specialist at The Motley Fool, said Amazon is likely to beat analysts' expectations in the first quarter largely due to e-commerce tailwinds that existed pre-pandemic.

But Sparks said deeper insights into whether Amazon's e-commerce growth can be sustained will come in the second quarter, when Amazon's earnings will be compared to the sales surge that occurred during the lockdowns of spring 2020. In the meantime, Sparks said Amazon will likely provide second-quarter sales guidance that points to a slowdown in e-commerce sales as vaccinations increase and COVID-19 cases decline.

Amazon previously said it anticipates a potential dip in first-quarter operating income on COVID-19-related expenses of about $2 million. But the company is typically conservative with its sales and operating income guidance, despite beating earnings guidance for several consecutive quarters, said Nick Shields, a senior analyst with Third Bridge who covers the retail sector.

Amazon tends to guide down as a way a "hedge their bets" in case pandemic-related costs, supply chain issues and an expected deceleration of e-commerce puts pressure on operating margins, Shields said. "Especially in a year like this, it's probably smarter for them to be cautious rather than be too optimistic," Shields said.

Despite Amazon's profit warning, the company's sales and operating income will likely come in "toward the higher end" of Amazon's guidance, said Tuna Amobi, a media and entertainment analyst at CFRA Research.

Significant traction gained from e-commerce growth, coupled with a pull-forward in online demand, will push Amazon sales higher, Amobi said. Amazon will also continue to benefit from the company's cloud computing unit, Amazon Web Services Inc. which has seen significant growth over the past year as companies moved to the cloud, he said.

EMarketer's Liu said Amazon's advertising business will drive growth in the first quarter. Amazon's share of the U.S. digital ad market was 10.71% as of 2021, according to eMarketer. That is still behind market leader Google LLC, which holds a 28.75% share of the market, followed by Facebook Inc. with a 25.37% share.

But Amazon is gaining traction as more online consumers search for products on Amazon. "That's a destination for them," she said.