From PEOPLE Magazine Click to enlarge
Sterling Diane Falconetti

JUNE 25

6 LBS. 15 OZ.

Having spent more than half her life honing her every move down to the millimeter on a 4-in.-wide balance beam, Shannon Miller does not leave much to chance. She's the kind of planner who color-coordinates her calendars, gets her packing done days ahead of time and recently gave her husband, John Falconetti, a fully stocked emergency diaper bag for his car. "I like structure," says the leader of the famed "Magnificent Seven" women's gymnastics team at the 1996 Olympic Games in Atlanta. Besides, she adds, "I went from pregnancy brain to chemo brain to pregnancy brain, so I have to be organized. I haven't had a straight thought in four years!"

It has been a humbling journey for the most decorated U.S. gymnast ever, whose world was turned upside down when she was diagnosed with a malignant tumor on her left ovary just 14 months after welcoming a son, Rocco, in 2009. After treatment that included the removal of the ovary and nine weeks of chemotherapy (see box), she is now cancer-free - and celebrating the arrival of her daughter Sterling, born June 25. "She is our miracle baby," says the seven-time Olympic medalist, 36. "She is such a blessing."

Her new baby girl is the biggest comeback yet for an athlete who built a career on them. Less than two years ago, she was happily raising Rocco at the family's home in Jacksonville, Fla., and launching a women's health-and-wellness company when "everything changed." Ready to try for baby No. 2, she had scheduled a visit with her obstetrician in December 2010. "The doctor told me he felt a cyst and that it was quite big," she says, "and that we needed to halt our baby plans. That sucks the wind out of you."

In hindsight Miller says she overlooked possible warning signs, including stomachaches and bloating. But as a new mom, "your body is in so much flux, you can't tell what the deal is."

Faced with the prospect of immediate surgery, Miller didn't hesitate when her doctor asked how aggressive she wanted him to be—even if it meant eliminating her chances of having more children. "She said, 'I want to make sure I'm here for my husband and son,' " recalls John, 45, a businessman who wed Miller in 2008 after meeting her at a charity golf tournament. In January 2011 doctors removed the tumor, along with her left ovary and fallopian tube. Then came the devastating news that the tumor was a higher-grade malignancy than originally thought, requiring nine weeks of an intense chemotherapy regimen. "Rocco grew up with me hooked up to my IV tube and port," says Miller. After losing her hair, "I feared that he would see me and start crying. Or not want to hug Mommy and be scarred for life." But the first time she revealed her bald head to him, "he just kept on playing!" she says. Still, she gets tearful recalling how he inspired her. "He's how I got up each day," she says. "I tried to really be 'on' when I was around him." She also relied on lessons she'd learned as a kid in an Edmond, Okla., gym. "I went back to the goal-setting of gymnastics," she says. "Thinking, 'If I can get up and walk around the dining room table today, that's a good day. If I can get dressed, that's a good day.' "

A year after finishing chemo, Miller's doctors gave her the green light to start trying for another baby. She had banked her eggs before treatment, but the couple didn't end up needing them. "I was surprised," she says of getting pregnant quickly, "but John and I had both put our trust in God."

Now the couple is settling into life with a newborn and a 3½-year-old. Rocco takes gymnastics, and already "he has really good balance. It's a little scary!" says Miller. Practicing at home one day, "he said, 'Mommy, you do a forward roll,' " recalls Miller. "He thought it was the funniest thing that I could do it." Her gratitude for such moments has grown out of what she has overcome. "In my gymnastics career, it was always about the next goal," she says. "Even when I won five medals in 1992, I was back in the gym the next day. I didn't stop and enjoy things along the way. I've started to do that much more. Now I'm grateful for each day."