Doctors said Kirstie Mills Tancock may not make it to the altar without a new set of lungs.
The 21-year-old from Devon in the United Kingdom has known since birth that she was living on borrowed time -- she was born with cystic fibrosis. And just days before her dream wedding last year, her lungs filled with a life-threatening infection.
"I have spent every moment living like it was my last," said Tancock, who, until her health spiraled downward, was a fit athlete and worked as a pole dance instructor.
"I take life as it comes," she said. "You never know what's going to happen. Just because you know your life will end doesn't mean you have control."
Television cameras followed Tancock for four months last year as she simultaneously planned her wedding and waited for a lung transplant. "Breathless Bride: Dying to Live" will air on TLC on Feb. 29 at 10 p.m. EST.
In the documentary, Tancock was confined to a wheelchair and hooked up around the clock to an IV for strong pain medication and antibiotics. Just days after her June 16 wedding, she was air lifted by medevac to a London hospital for a lifesaving double lung transplant.
"Kirstie is a complete fighter," said her husband Stuart Tancock, 27, and a sports store manager, in the documentary. "You can't put her down ? She'll fight for anything."
Tancock has known since a young age that her life was expected to be short. She was born with cystic fibrosis, an inherited chronic disease that affects the lungs and digestive system. About 30,000 children and adults in the United States have the disease.
About 1,000 new cases are diagnosed each year in the U.S., and about one in three people with the disease will die waiting for a lung transplant.
A defective gene and its protein product cause the body to produce unusually thick, sticky mucus that clogs the lungs and leads to life-threatening infections, according to the Cystic Fibrosis Foundation. The disease also obstructs the pancreas and stops natural enzymes from helping the body break down and absorb food.
Only a half century ago, few children with CF lived to attend elementary school. Today, medical advances have extended the average life span of someone with CF well into their 30s and 40s.
According to the CF Patient Registry, nearly 1,600 people with the disease have received lung transplants since 1991. As many as 90 percent are alive one year after transplantation and half are still living after five years.
As Tancock's story begins, the clock is ticking. Her incessant cough disrupts her every activity as she gasps for air, even as she rides as a passenger in a car for some pre-wedding shopping.
At night she wears a mask so that oxygen can be forced into her lungs while she sleeps.
Her lung function dropped to 16 percent of a normal person's, according to Dr. Nick Withers, who treated Tancock and was featured on "Dying to Breathe."
CF patients are referred for transplantation when lung function drops to 33 percent. "She is living on a knife edge," he says. "Anything can tip her over."
Tancock is optimistic, but also a "realist."
"I didn't expect to be here at 21," she says, with her oxygen tank in tow. "But that's not the worst thing -- I'd love to have working lungs ? CF has made me who I am, but I'd trade it in a heartbeat."