A baby has been born using sperm frozen for 21 years in what researchers hailed as a world record in fertility treatment.
The child, a boy, was born following IVF after the father had his sperm frozen in 1979 before being treated for testicular cancer. The successful birth is being claimed as a record for the longest period that sperm has been kept frozen and resulted in a live birth. It also demonstrates how modern fertility treatment is extending the boundaries of reproductive life.
The boy was born two years ago but details have been released for the first time today by doctors at St Mary's Hospital and the Christie Hospital in Manchester who treated the couple. Writing in the journal Human Reproduction, the doctors say: "We believe this is the longest period of sperm cryopreservation resulting in a live birth so far reported in the scientific literature."
The couple have requested anonymity but were last night considering several offers of cash from media organisations for their story.
The father, now 42, was treated for testicular cancer at the age of 17 with surgery, radiotherapy and chemotherapy which left him sterile. Before treatment began he deposited five ampoules of sperm which were kept deep-frozen in long-term storage. The treatment lasted two years and he had regular checks for the next decade before being discharged from follow-up in 1992, aged 30.
He and his partner then considered having a family and were referred to the fertility unit at St Mary's Hospital in Manchester in 1995. Elizabeth Pease, a consultant in reproductive medicine, said: "Their first concern was whether, when it was defrosted, the sperm was going to be viable."
The defrosted sperm was found to be in good condition and the woman was inseminated with it to see if this alone would prove successful. When it did not, the couple joined the waiting list for IVF.
They were accepted for treatment three years later in 1998 when the man was 36 and his partner 28. They had four attempts at ICSI - the method which involves injecting a sperm directly into the egg.
Embryos were created and transferred to the woman on three of these occasions but failed to implant. Two embryos from the last attempt were frozen and two years later the couple had them thawed and impregnated in 2001. Their healthy son was born in 2002.
Dr Pease said the couple were "over the moon" when they learnt their treatment had been successful. She said their example offered hope to young cancer patients worried about their fertility in the future.
"For many patients it might not cross their mind [to store their sperm] because of more immediate concerns about their health. The important thing is that it is an option which can be offered to them," she said.
"There is not much information about success rates using sperm frozen for many years so we will be interested to see what happens next."
The average age of men storing their sperm because of treatment for cancer or other conditions is 24. Under UK regulations from the Human Fertilisation and Embryology Authority, frozen sperm can be stored until a man is 55.