A US woman has successfully delivered a baby with a 25-year-old frozen embryo -- the longest known frozen human embryo.

Frozen as embryo on October 14, 1992, Emma Wren was born to Tina Gibson on November 25, 2017, weighing 6 pounds 8 ounces and measuring 20 inches long. "Do you realise I'm only 25? This embryo and I could have been best friends," Gibson, a resident of East Tennessee, was quoted as telling CNN. "I just wanted a baby. I don't care if it's a world record or not." Previously, the oldest known frozen embryo that came to successful birth was 20 years old. When Gibson got married seven years ago, her husband had cystic fibrosis, a condition that can make men infertile. The couple decided to adopt a child. In the meantime, they would foster several children. 

Then, last year, her father told them about embryo adoption, where an embryo will be implanted in the body helping them to carry a baby. In August 2016, Gibson submitted an application for the adoption, and by spring had three embryos from the same anonymous donor transferred into her uterus. After a series of medical examinations to see whether her uterus would be physically capable of receiving an implanted embryo, she was declared eligible for implantation in January. It was only when she was preparing for the transfer that the doctor explained that the embryos Gibson had could lead to a "world record", she told CNN.