An Air Canada flight arrived in Tokyo with an extra passenger after an expectant mother unexpectedly gave birth as the plane flew over the Pacific Ocean.

A doctor who happened to be on board the flight from Calgary – which arrived in Japan on Mother’s Day – delivered the baby girl after the crew asked passengers for medical help when Ada Guan went into labor.

The 23-year-old mother from Victoria, British Columbia, and newborn baby Chloe were taken to a hospital, where they spent the night and were reportedly doing well after the surprise delivery.

'Something fell out of me,' Guan reportedly said during the birth.

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Ada Guan, 23 (center), and boyfriend Wesley Branch (left) said they had no idea that they were pregnant with baby Chloe (center) when they boarded a plane from Calgary to Tokyo

Guan had noticed weight gain and taken a pregnancy test several weeks before the dramatic birth at 36,000 feet, but the test came back negative and a visit to the doctor also didn't reveal she was expecting

After the plane landed at Narita International Airport Monday afternoon, the baby’s overwhelmed father Wesley Branch told reporters that he ‘couldn’t imagine this just happened, completely unexpectedly.'

His girlfriend Guan had seen a doctor before heading for a holiday in Japan and took a pregnancy test several weeks ago that came back negative after recently gaining a bit of weight, according to the Calgary Sun.

‘It turned out that we have a beautiful baby girl,’ Wesley said.

'I saw her just two weeks ago and she doesn’t look at all pregnant — she’s just tiny little thing,' new grandma Sandra Branch said.

'She was absolutely petrified — she thought she was dying, she didn’t know what was going on,' Branch said after speaking with her son, adding that she couldn't be happier about her grandchild.

Baby Chloe became an instant celebrity on the plane after three doctors who happened to be on board helped deliver her after her mother's stomach pain escalated into a medical emergency

Branch said that he passed out after lifting up his girlfriend's pants and seeing that he had unexpectedly become a father

The young mother requested help after stomach pain she had back in Canada escalated into a medical emergency.

She was upgraded to first class for the birth at 36,000 feet, according to Global News.

'I lifted up her pants and I saw a head and then I heard waahhhh,' her boyfriend said.

'And I'm like oh my god, I think we have a kid,' he added, admitting that he 'passed right out' after learning about his daughter.

Air Canada actually prohibits women from being on a plane after the 36th week of pregnancy, according to CBC.

'Footage from a Japanese television station showed the mum being taken off the Boeing 767-300 in a wheelchair as the baby’s father walked behind her and cradled the baby in his arms.

Branch was seen on Japanese television holding his new born as his girlfriend was escorted off of the plane

Recovery: Despite the dramatic ordeal, Branch said that his girlfriend and daughter are doing well at hospital. The couple will have to wait a week to return to Canada with their baby

He waved to reporters and kissed the girl, and later showed media a mobile phone picture of the baby.

Chloe has Canadian citizenship because of the flight's origin, though she could also be eligible for American citizenship if she was born above Hawaii.

A female passenger told Japanese media: ‘ Everyone was clapping their hands. She’s such a cute baby with big eyes.’

Given the situation on board, flight ACA9 was given priority at Tokyo’s primary airport and landed 30 minutes ahead of schedule at the conclusion of its 10-hour journey from Canada.

The new parents will have a week to wait and deal with their surprise before returning home with their baby girl due to the newborn's sensitive ears.