The woman requested assistance from the crew minutes before it was due to land yesterday at Bucharest's Otopeni airport, Romania's busiest, the eastern European budget airline said in a statement.
"During descent and while taxiing to the terminal, the passenger was assisted on a back row of the aircraft by a crew member and a doctor who was travelling on the same flight," it said.
The airline did not specify the passenger's nationality or age but a spokeswoman said she was nine months pregant.
"While this mother and her newborn baby seem well, we urge all our pregnant mothers not to risk their well-being and not to conceal their pregnancy," the statement said.
Passengers must produce a certificate from a doctor if they are travelling after their 28th week of pregnancy, and cannot travel after their 34th week of pregnancy, the airline said.