It was a happy Mother's Day for a Canadian woman on an Air Canada plane that left Calgary en route to Tokyo after she gave birth to a healthy girl somewhere over the Pacific Ocean on Sunday.

The birth was aided by physicians who were passengers on Flight AC009, and by a ground-based medical team, Air Canada spokeswoman Angela Mah said in an email.

The plane was given landing priority and touched down 30 minutes ahead of schedule, said reports.

"I couldn't imagine, this just happened completely unexpectedly. It turned out we have a little baby, beautiful girl," said the father, Wesley Branch, to Japanese reporters as he held the baby.  

"Her name is Chloe."

Ada Guan, 23, was taken to the hospital with her newborn. 

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

"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.

On its website, Air Canada says women having a normal pregnancy and no history of early labour can fly up to and including their 36th week. A typical pregnancy lasts 38 to 40 weeks.

The airline tweeted that mom and child are doing well. 

The folks at CBC's This Hour Has 22 Minutes couldn't resist this quip on Twitter: