The women, including 13 Australians, were examined at Hamad International Airport on October 2 after Qatar Airways Flight QR908 to Sydney was delayed.
Qatar offered no immediate explanation of how officials decided to perform invasive vaginal examinations on the women.
Human rights activists describe such examinations conducted under duress as equivalent to sexual assault.
The small, energy-rich country on the Arabian Peninsula is a major hub for East-West travel and host nation for the 2022 World Cup, and Hamad International Airport is the main hub for state-owned long-haul carrier Qatar Airways.
In Qatar, like much of the Middle East, sex outside of marriage is a criminal act.
Migrant workers in the past have hidden pregnancies and tried to travel abroad to give birth, and others have abandoned their babies anonymously to avoid prison.
Qatar’s Government Communications Office issued a statement early on Wednesday that authorities discovered the newborn “concealed in a plastic bag and buried under garbage” at the airport.
It called the discovery an “egregious and life-threatening violation of the law”.
The statement said officials searched for the baby’s parents, “including on flights in the vicinity of where the newborn was found”.
The government said: “While the aim of the urgently decided search was to prevent the perpetrators of the horrible crime from escaping, the state of Qatar regrets any distress or infringement on the personal freedoms of any traveller caused by this action.”
Qatar said its investigation would be shared internationally.
Australia has described the situation as inappropriate and beyond circumstances in which the women could give free and informed consent, and the country’s federal police also are examining the matter.