Woman carries baby for her twin sister who had hysterectomy due to pregnancy-related cancer

The sisters say "a lot of love" is bringing their son and nephew into the world.

When Sarah Sharp was diagnosed in 2018 with a rare gynecological cancer and told unexpectedly that she may need an emergency hysterectomy, her twin sister, Cathey Stoner, was there for her.

"Cathey rushed to the emergency room to be by my side," Sharp, now 33, told "Good Morning America." "And that was the first time she said to me, 'If you need to have a hysterectomy, I'll have your babies.'"

Just weeks earlier, Sharp, who like Stoner lives in the Nashville area, had been diagnosed with choriocarcinoma, a rare and fast-growing cancer that occurs in a woman's uterus.

It was a shocking diagnosis, not only because doctors told her the cancer likely came from her first and only pregnancy, with her now 4-year-old daughter Charlotte, but also because the cancer was likely to rob her of any future pregnancies.

"The diagnosis pretty much rocked my world," said Sharp, who went to her OBGYN thinking she had a miscarriage because she was experiencing bleeding and had a positive pregnancy test. "My first thought was just survival and getting through treatment."

"But it broke me," she added "because my husband and I wanted to have more kids. My daughter had just turned 1."

Sharp underwent seven rounds of chemotherapy in an attempt to beat the cancer while also saving her uterus. She was declared cancer free in December 2018, just before her 31st birthday, but by her first checkup, in January, the cancer had returned.

She began a new course of chemotherapy and also underwent a hysterectomy, which successfully removed the cancer but left her without the hope of giving birth to another child.

"It was kind of a déjà vu moment where I found Cathey and my husband by my bedside again," said Sharp, referring to the moment a year before in the emergency room. "And that's when Cathey said, 'I'm serious this time. I will have your babies.'"

"We kind of laughed a little bit again but for me, in the back of my mind, it was something to hold onto," she said. "It was something to help me move myself forward mentally. It was hope and grace and the future all in one."

Now nearly three years after her diagnosis, Sharp is both cancer free and preparing to become a mom again.

Her sister, Stoner, is due to give birth in August to John Ryder, the biological son of Sharp and her husband.

"From the beginning I've felt differently in this pregnancy because I know it's my nephew and not my son, and I have loved every step of the way," said Stoner, who is the gestational carrier. "I tell people, 'I'm just carrying my nephew.'"

Stoner said she and her husband, parents of a 4-year-old son and a 6-year-old daughter, had no hesitation about helping her sister expand her family in any way they could, whether it was Stoner as the carrier or someone else.

"We decided to knock on the doors and see if they opened," said Stoner. "There was a lot of waiting, but it went really smooth and, in October, they said we were ready to go."

By the end of last year, the two sisters were celebrating the news that Stoner was pregnant.

"To be able to go to the doctor for such a happy reason is really healing for all of us," said Stoner, who has shared every step of the pregnancy with Sharp, who has been to every doctors' appointment. "It's been an easy pregnancy so we've gotten to soak up the good stuff."

Sharp and her husband will be in the delivery room in August alongside Stoner and her husband as they welcome their son and nephew, respectively.

"We feel so unbelievably honored to be his parents and raise him," said Sharp. "A lot of love brought him here."

Sharp, an artist and architectural design representative, and Stoner, a registered dietitian, said they have learned firsthand through their journey the importance of women listening to their bodies.

They are now the co-hosts of a podcast, "Talk to Me Sister," that's focused on women's health and advocacy through the lens of their own journey.

"I'm lucky I had a twin sister who is educated in women's health and who has had babies in the past and miscarriages in the past, because had I not talked to my sister, I'm not sure I would have gone to the doctor," said Sharp of the doctor's visit that led to her cancer diagnosis. "What I've learned along the way is even if there's a light intuition that this may not be normal for me, I listen to it. it's usually my body telling me that something is off."

Choriocarcinoma, which affects 2 to 7 of every 100,000 pregnancies in the United States, has a low cure rate if it is not caught early and spreads outside of the uterus, according to the American Cancer Society.

"In the U.S., this is just a rare complication of pregnancy that many women don't know anything about unless they are faced with this diagnosis," said Dr. Alpa Nick, a Nashville-based gynecological oncologist who treated Sharp. "The most important thing is continuing your annual care and your well-women care after pregnancy. Keep your postpartum follow-up [appointment] and stay in touch with your doctor."

Nick, like Sharp and Stoner, also stressed the importance of women using their voice when faced with a diagnosis like this that threatens both their lives and their fertility.

"If fertility preservation is important, the first thing they have to do is say it out loud to their oncologist, and the earlier the better," said Nick. "With Sarah, we were able to stay focused on what her goals were and think about her cancer treatment in terms of survival, but also in terms of what she would want down the road after she survived this."