"Losing my hair was a very scary issue, but it was nothing in comparison to losing the ability to have a family," she said.
Each year, about 40,000 women in their reproductive years are diagnosed with breast cancer. Doctors have traditionally discouraged them from getting pregnant because of concerns that the extra hormones produced, like estrogen, might fuel the cancer. Chemotherapy can also damage the ovaries and make conception difficult.
Dr. Kutluk Oktay has spent the last 15 years figuring out how women with breast cancer can have children.
How have things changed?
"Today, we cannot imagine treating a young cancer patient without thinking of fertility preservation," he tells CBS News medical correspondent Dr. Jon LaPook.
There's a precious window of opportunity between breast cancer surgery and starting chemotherapy. Heidi and her husband took advantage of this time to have her eggs harvested and fertilized using new techniques that don't rev up the hormones that could rekindle the cancer.
"They can freeze their embryos, they can freeze their eggs, or they can freeze their ovarian tissue for future transplantation," explains Dr. Oktay.
Heidi decided to freeze her embryos and try using a surrogate to carry her baby. Today, she has a 9-month-old daughter, Ruby Kate Kessler.
The long-term safety of fertility treatment and pregnancy in women who have had breast cancer is still being studied. The treatments are pricey - from $10,000 to $15,000 - and often are not covered by insurance.
But Heidi had faith she could beat breast cancer and become a mother.
"I can't believe she's here," she says of her daughter. "I can't believe what we went through, what she went through to get here."