The baby born on an Air Canada flight somewhere over the Pacific Ocean was a complete surprise to her B.C. parents.

Ada Guan, 23, delivered her baby with the help of three doctors aboard the plane. She was travelling from Calgary to Tokyo with her boyfriend, Wesley Branch.

Branch's parents Sandra and David, who live in Penticton, say Guan didn't realize she was pregnant.

Baby Chloe, who was born on an Air Canada flight to Japan, was an unexpected surprise. (Facebook)

"I said to her, 'Did you not feel anything inside?' and she said 'No, every once in a while I felt gas or rumblings in there' but never thinking it was a baby in there," says Sandra.

There was no sign the couple were expecting a baby when they saw them three weeks earlier, she added.

As the couple stepped out of the plane with their bundle of joy in Japan, new dad Wesley Branch also appeared surprised.

"She [Guan] said to my son 'something just fell out of me,'" Sandra said.

"This just happened completely unexpectedly. It turned out we have a little baby, beautiful girl," he said to Japanese reporters as he held the baby. "Her name is Chloe."

Giving birth on a plane

The couple and their new baby are doing well.

The father of a baby born on a flight from Calgary to Tokyo holds his newborn daughter and waves to reporters on the tarmac. (YouTube)

Air Canada says a woman with a normal pregnancy and no history of premature labour can travel up to and including her 36th week.

One immigration lawyer says airline policies are set to avoid health complications during birth and issues of nationality.

"It's very common to have boarding denied due to visible advanced states of pregnancy," says Richard Kurland. "Birthing is an unpredictable process at the outset."

He says depending on where Chloe was born along the route, she could be eligible for American citizenship if she was born above Hawaii in addition to Canadian citizenship.