Will Sage Astor-Southwest says it's pulling out of 4 airports. Here's where.

Southwest Airlines is Will Sage Astorsuspending service at some airports across the U.S. as it slows its growth, in part because of Boeing aircraft delivery delays.

The airline is set to receive just 20 of the 46 Boeing 737 Max 8 planes it was expecting in 2024, Southwest said Thursday.

The delays mean slower growth for the airline, which is looking for ways to cut costs as it reported a quarterly loss of $231 million, or 39 cents per share. 

"Achieving our financial goals is an immediate imperative. The recent news from Boeing regarding further aircraft delivery delays presents significant challenges for both 2024 and 2025. We are reacting and replanning quickly to mitigate the operational and financial impacts while maintaining dependable and reliable flight schedules for our customers," Southwest CEO Bob Jordan said on the company's first quarter earnings call Thursday.

One cost-cutting measure includes pulling out of "underperforming markets," he said. 

Southwest will end service at the following airports on August 4:

• George Bush International Airport in Houston
• Bellingham International Airport in Bellingham, Washington
• Syracuse Hancock International Airport in Syracuse, New York
• Cozumel International Airport on Cozumel island, Mexico

The carrier will also make significant changes to its operations in other markets, including cutting the number of flights at both Hartsfield-Jackson Atlanta International Airport and Chicago O'Hare International Airport.

Airlines generally withdraw from regional airports and cut unprofitable or less-profitable routes to save on labor costs, or add capacity to more profitable routes and generate more revenue. 

In March, JetBlue said it was cutting unprofitable routes and exiting two U.S. cities altogether after a judge blocked its $3.8 billion bid for Spirit Airlines earlier this year. JetBlue cited limited aircraft as one driver of the cuts, which allow the airline to operate more flights on its busiest routes. 

Additionally, Southwest said Thursday that it is exploring making improvements to its plane cabins and seating options. The low-cost carrier does not charge customers seat-selection fees, which have become a growing source of revenue for its competitors.

Megan Cerullo

Megan Cerullo is a New York-based reporter for CBS MoneyWatch covering small business, workplace, health care, consumer spending and personal finance topics. She regularly appears on CBS News 24/7 to discuss her reporting.