A baby girl was born after being conceived using sperm that has been kept frozen for 25 years – the longest that sperm has been kept frozen and then successfully used for IVF in the UK.

Proud dad Richard Pott had his sperm frozen at the age of 21 after he developed testicular cancer, reports the Telegraph.

Doctors advised that he freeze samples of his sperm before having the cancer treatment, as chemotherapy carries a high risk of infertility.

Although becoming a father wasn’t a priority for him then, two decades later Richard got to finally use his frozen ‘rainy day’ sperm to become father to daughter Vivienne in a double IVF first in Britain.

Thirteen-month old Vivienne was conceived using the thawed sperm. Three embryos were created using the thawed sperm before being transferred into the womb of mother Rebecca, who herself suffers from a female fertility problem, endometriosis.

Despite the first transfer not being a success, the couple made a last ditch attempt by having two of the frozen and defrosted embryos implanted. This time, it was a success.

"I really want our story to give hope to other people who are in similar circumstances," Richard told the Telegraph.

Vivienne was born nine weeks premature, weighing just 1,1kg at birth but has since grown into a healthy child.

Vivienne is the couple’s second child, as they are also parents to Harry, 5, who was conceived after two rounds of IVF.

“We believe this is the longest that sperm has been frozen and used successfully in Britain,” Dr Tarek El-Toukhy of Guy’s and St Thomas’ hospital told the Telegraph.

According to guidelines by the National Institute for Health and Clinical Excellence issued in 2004, all young men having cancer treatment should be offered the chance to have their sperm frozen for future use.

Frozen sperm must be stored in extremely cold temperatures (-196 F) after it has been examined before being frozen to assess total number of moving sperm. Immediately after the sperm has been analysed, it is then divided into smaller batches and transferred into vials for freezing.

A special compound (a cryoprotectant) is added to aid the freezing process. The test tubes are gradually frozen in liquid nitrogen vapor. After 30 to 60 minutes they are transferred into liquid nitrogen tanks for permanent frozen storage.