The CEO of American appliance maker Whirlpool told CNBC's Jim Cramer on Thursday he's "starting to get worried" the U.S. labor market could face structural challenges in the years ahead, even after various pandemic-related hurdles have been cleared.

In an interview on "Mad Money," Cramer asked Whirlpool CEO Marc Bitzer whether he was concerned about the country's declining birthrate, which fell for a sixth straight year in 2020, and its long-term implications for the world's largest economy.

"Demographics drive consumption, but frankly also employment. ... We're producing 80% of what we sell in the U.S. in the U.S., so have more than 20,000 employees in the U.S.," Bitzer said. "I'm starting to get worried that the labor shortage start becoming structural, so yes, demographics are a little bit of a worry down the road."

There are currently millions of jobs open in the U.S., but many employers have said filling them has proved to be harder than expected even as a broader range of economic activity picks up from Covid-linked slowdowns.

Multiple factors are behind the current labor-market situation, economists say, including workers having health concerns, needing to juggle care responsibilities and unsatisfactory wage offerings at vacant positions. Early retirements and savings built up during the pandemic also may be limiting the number of people returning to the workforce. Even though the Covid pandemic's damaged the economy quickly, experts stress it will take time for these barriers to entry to subside.

Bitzer's comments hit on a more fundamental, overarching challenge the American economy may face in the years ahead, and he's not the first executive to discuss it with Cramer.

Last week on "Mad Money," Domino's Pizza CEO Ritch Allison raised concerns about "minimal population growth organically" in the U.S. combined with a slowdown in immigration. Cramer later described his conversation with Allison as "shocking" and "sobering," suggesting the issues were not getting enough attention.

Cramer made a similar point Thursday when speaking with Whirlpool's Bitzer, who appeared on "Mad Money" after the Michigan-based company reported mixed third-quarter results. Earnings per share of $6.68 topped Wall Street's estimates of $6.12, while revenue of $5.49 billion fell short of the projected $5.74 billion.

Shares of Whirlpool fell more than 2% in after-hours trading, as investors reacted to the quarterly numbers. The stock closed the regular session Thursday down 0.64% at $207.90 per share. It's up about 15% year to date.