A female passenger's complaint on social media that she had been mistaken for being pregnant has prompted an apology from Australian-based carrier Jetstar Airways.

New Zealand native Grethe Andersen was boarding a flight from Wellington to Auckland last Sunday (Oct 25) when a male flight attendant popped the embarrasing question.

According to Ms Andersen, who was wearing a fitted dress, he had allegedly motioned to his stomach and asked "how many weeks are you?"

Left humiliated by the experience, the 24-year-old claimed she did not receive an apology from the attendant. A cabin crew leader whom she spoke to when the plane landed said the airline, for safety reasons, had a policy of asking women if they were more than 28 weeks pregnant.

Ms Andersen subsequently took to social media to voice her disappointment. Her post on Jetstar's Facebook page attracted messages of support from other women.

"As a woman, it's not a good feeling to be asked if you're pregnant when you're not," she wrote.

"I used to be quite heavily overweight and even then was never met by such a rude question and especially no remorse from the flight attendant."

Local media reported that the airline got in touch with Ms Andersen on Tuesday evening to apologise, and offered her a NZ$100 (S$93) voucher.

While she was appreciative of the gesture, she felt Jetstar had to learn "new ways" to handle similar sensitive incidents.

"It is a tough subject to approach but it can be done differently," she added.

In October 2012, passenger Kelsey Hughes was embarrassed on a Jetstar flight when a flight attendant thought she was pregnant and demanded a doctor's letter to certify that she was fit to fly.