The form read: “The passenger has been observed to have a body size/shape resembling to a pregnant lady,” according to Ms. Nishida, who said she showed airline employees her return plane ticket, but to no avail.

“I was then led by a female in plainclothes, who claimed to be the medical practitioner, to a public restroom,” she wrote. “I was handed a pregnancy test and when the result came out negative, she failed to record this on the medical form and instructed me to throw the test into the trash. Satisfied that I had no baby in me, the airline staff finally issued me a boarding pass.”

The airline, which Cathay Pacific bought in July, said the pregnancy test requirement arose early last year.

“In response to concerns raised by authorities in Saipan, we took actions on flights to Saipan from February 2019 to help ensure U.S. immigration laws were not being undermined,” the airline said. “Under our new management, we recognize the significant concerns this practice has caused. We have immediately suspended the practice while we review it. We’d like to apologize for the distress caused.”

The United States Department of Homeland Security did not immediately respond to a request for comment on Thursday night.

Ms. Nishida wrote that she was well aware of Saipan’s reputation as a “hot spot” for birth tourism, but that she was appalled by the way the airline had treated her.

“Coming back to Saipan has always been a happy time for me as I look forward to seeing my family and catching up with friends,” she wrote. “But after this incident, I can only think of how I will be suspected, investigated and humiliated before I can return to a place I consider home.”