When embryos created by in vitro fertilisation are unused, they are usually destroyed or donated to science. However, a Texas family is reaping the reward of a third option—embryo adoption.

Liz and Kevin Krainman were unable to have biological children, and were considering adopting a child. Then, Liz discovered a way for her to experience pregnancy and childbirth.

"When I first discovered embryo adoption, it was like Christmas morning," she told ABC News. "Something just clicked that was like I had no idea this existed, [that] I could be pregnant and I could have a child that's adopted."

Liz, 33, carried and birthed a now four-month-old daughter, Sammy, who was created by a 2006 IVF procedure.

Libby and Tony Kranz underwent five rounds of IVF nearly ten years ago, and had four unused embryos. Known as "snowflake babies," the embryos were cryopreserved and put up for adoption. Baby Sammy spent seven years on ice.

"Just knowing that she was frozen for so long as a little ball of cells and then awakened, that process just blows my mind," Liz said. "Love is what made her. The love of so many people went into creating her and bringing her here."

Mrs Krantz, 35, said she is just as thrilled about Sammy's birth.

"We gave them a gift and people like to say, 'Oh, they gave such a generous gift,' but they gave us a gift too," she explained. "They gave us the perfect landing spot for these embryos.

"It's a gift that we gave ourselves, I guess, because we did the right thing and we know it," she continued. "I'm proud of it and it's a nice feeling to be proud of yourself for something."

"They are God's gift from heaven!" Liz said of "snowflake babies."

"Even though Sammy is no longer frozen, she is always going to be my Sammy Snowflake."