Four months after her miscarriage, Jenni Masterson's pregnancy outlook dropped even further on the healthy spectrum.

She was diagnosed with lymphangioleiomyomatosis-or LAM-a rare lung disease primarily affecting women in their 30s and 40s. It's basically the invasion of smooth muscle cells into the lung tissue, resulting in the formation of dead pockets of air space where air exchange can't occur. As the cysts enlarge, less functional lung tissue remains, and can lead to shortness of breath at best and spontaneous lung collapse at worst.

Masterson had already suffered multiple lung collapses.

"The immediate recommendation for women who have LAM is not to get pregnant, as they think estrogen may accelerate the course of this progressive disease, which currently has no effective treatment," Masterson says.

And since LAM can progress very quickly, she didn't know how long she'd have with a baby-if she could make it through the pregnancy at all.

If she were to get pregnant, there would be more stress on her lungs during the pregnancy and delivery. But after additional testing determined that the condition wasn't the hereditary form, Masterson decided to take the risk and try to have the baby she'd always wanted.

She had an uneventful pregnancy, with her water breaking during a prenatal yoga class a week before her due date.

Dylan just turned 2 and Masterson's health has stayed exactly the same. She currently has normal lung function. In addition to looking after her toddler, she continues to work 32 hours a week as a physical therapist.

She has no regrets.

"I try to live my life as if I don't have LAM, while at the same time living in the moment because I know things could change at any time," she says. "I am thankful for every day that I can chase my little boy without having to wear oxygen tubing, and I hope I have the gift of time with him."