In December of 2012, a week before McCarthy was due to give birth to her first child, she was diagnosed with an aggressive form of breast cancer.
"You don't even know here to start. I didn't know. Do I have the baby first? To see an oncologist first? Do I have surgery first? Trying to plan all those things together was unreal," Kelly McCarthy, breast cancer survivor, said.
"After she was diagnosed, we spent a lot of time focusing on her," Maurer, who was also pregnant with her first child at the time, said. But then doctors suggested she also get tested. That's when Maurer got the bad news.
"We sat down we pulled out a folder and said you just do everything together don't you? And Kelly lost it," Maurer said.
Maurer's cancer was caught at a very early stage. She chose to have a double mastectomy.
After chemo, surgery and radiation, McCarthy is about to undergo breast reconstruction in November. But she doesn't have enough skin and tissue, and cancer treatment prevents her from using anti-rejection drugs. University of Chicago's Dr. David Song had an idea: ask her twin sister.
"We have a very unique situation. It's only been done three or four times in the history of medicine, where we can borrow tissue from one identical twin to another to actually reconstruct a breast," Dr. Song said.
"So, Kristen is amazingly going to go have another surgery for me," McCarthy said.
"This will be the beginning of a new chapter, closure for the two years we've had," Maurer said.