Jenni Lake, an Idaho teen who stopped her cancer treatments to avoid aborting her pregnancy, died 12 days after she gave birth to a baby boy she named Chad Michael.

She passed away on Nov. 21, with no regrets about the decision to choose her son's life over her own, and to risk everything she'd hoped for in the new hope that he might be healthy.

This is her story.

Rash of Tumors Discovered

Jenni Lake was diagnosed with cancer when she was 16 years old.

Lake was a sophomore at Pocatello High School when she began to get painful migraines. After visiting her family doctor, she traveled to Salt Lake City for an MRI. There, a scan revealed a two-centimeter mass nestled in her brain.

 Lake's biopsy revealed stage three astrocytoma, a form of cancer centered in the brain and spinal cord that is almost always fatal. She had three tumors in her brain and three on her spine. Chemo and radiation treatments had to begin immediately.

Even with the intensive treatments, doctor told her she had about a 30 percent chance of living two years. Lake was also told that even if the cancer treatments worked, she would be left infertile.

When they told her she might not be able to have kids, she got upset, Lake's mother Diana Phillips said.

Her father Mike, however (Lake's parents are divorced), noted that when doctors told her the slim odds of surviving, she was calm. She didn't break down and cry or anything, he said.

'Jenni's Journey'

Jenni Lake began receiving cancer treatment in 2009, and boyfriend Nathan Wittman stuck with her the whole time. She even began recording videos of her struggle with cancer in a series of YouTube clips called Jenni's Journey, before her treatments left her too weak to continue.

Nor was life at school any easier.

The rumors started flying around, like Nathan was only with her because she had cancer, said Jenni's older sister, Ashlee Lake, 20.

But when Wittman took her to the prom in 2010, her tumors were shrinking significantly, and the pair began dreaming of opening a restaurant or a gallery in the future. It seemed, to Lake's family, as though the Idaho teen might just pull through.

Then the stomach cramps began, and vomiting, and the headaches returned.

A Terrible Choice

A visit to the local hospital confirmed Lake's fears: the 17-year-old was pregnant. Lake and Wittman, having been told she was almost certainly unable to conceive a child, had not bothered using protection.

We could hear Jenni just bawling in her room, sister Kaisee, 19, said.

Jenni Lake was faced with a tremendous decision. Her oncologist told her that the cancer treatments keeping her alive could not be given to a pregnant woman without damaging or killing the fetus.

She had two options: get an abortion and continue being treated for cancer, or keep her pregnancy and prepare to die.

Her family believed that since the tumors had already starting to shrink, and the baby was ten weeks old, she had a strong chance of carrying the baby to term and then starting the cancer treatment again.

'I did what I was supposed to do.'

So Jenni Lake chose option two, and paid for it with her life.

At the end of her pregnancy, Lake weighed only 108 pounds. He cancer has come back with a vengeance in the many months since she stopped treatment, and she had already begun to reconcile herself to death.

I'm done, Lake told her nurse just before delivering a healthy baby boy, whom she and Wittman named Chad Michael. I did what I was supposed to do. My baby is going to get here safe.

Jenni Lake died on Nov. 21, 2011, shortly before Thanksgiving Day. She was not yet 18 years old.

Jenni Lake's Legacy

In the month since her death, Jenni Lake's family and friends continue to insist that her legacy is not one of tragedy, but of heroic sacrifice. And that is the legacy they will be passing on to her son Chad.

I want him to know everything about her, and what she did, Phillips told CBS.

The family gathered at their ranch style home in Pacotello, Idaho this Christmas with a tree decorated with ornaments that reminded them of Jenni, who passed away in a bedroom just down the hall.

Lake's boyfriend, has legal custody of his child, cared for primarily by his mother Alexia Wittman. Nathan and Jenni named their healthy baby boy Chad Michael in honor of their fathers.

'I can kind of see him.'

As Jenni Lake began to fade away, the returning astrocytoma ravaging her body and making her weaker by the day, family members report that she never showed any regret for her decision. Nor did her vision, sometimes a casualty of the final stages, fade in the final days of her illness.

When Jenni Lake's baby son was placed beside her for the last time, her father says she smiled at Chad Michael, her pride and joy, the reason she was about to die.

I can kind of see him, she told her father. It would be the last words she ever said.

Below, watch Jenni Lake's first videos as she struggled with stage three cancer. Lake's family has left the videos up on YouTube.

Jenni's Journey: Jenni Lake's First Video

Diana Phillips: Lunch With Jenni