A woman has given birth to a baby boy who was conceived using sperm frozen for 21 years.
BBC News Online examines the process.
Why did the man's sperm need to be put into storage?
He developed testicular cancer in 1979 at the age of 17.
Although testicular cancer can be treated through surgery, and radiotherapy or chemotherapy, the treatment can damage the sperm, rendering some patients infertile, and increasing the chances of abnormalities in others.
As a precaution, many patients are offered the chance to put their sperm into storage before treatment begins.
Rates of testicular cancer have risen sharply in recent years.
However, if picked up at an early stage, most people make a full recovery and many people who undergo treatment do retain full fertility.
What happened next?
The man got married, and the couple decided to try for a child in the late 1990s.
Three attempts at IVF resulted in the creation of embryos, but they failed to implant in the womb.
On the fourth attempt, enough embryos were produced to allow three to be frozen. Two were thawed and transplanted into the womb in 2001.
The woman became pregnant and gave birth to a healthy son two years ago.
It is believed to be oldest sperm ever used successfully in IVF treatment.
Which IVF technique was used?
Doctors only had a limited supply of sperm from the man, so to maximise the chances of a successful pregnancy they used a technique called Intracytoplasmic sperm injection (ICSI).
This involves injecting a single sperm directly into an egg to ensure fertilisation.
The technique was only developed in 1992 - 13 years after the sperm was originally stored.
Is it safe to freeze sperm?
Sperm kept in the deep freeze has no apparent sell-by date. Freezing does not appear to affect its quality at all.
Also, there is no evidence to suggest that children born from frozen sperm are at any greater risk of abnormal development.
Scientists warn that scientific knowledge in this field is still developing, but in theory sperm could be stored for centuries and still be perfectly functional.
The main problem with IVF is that it tends to lead to a higher rate of multiple births - because doctors implant more than one embryo to maximise the chances of a successful birth.
Multiple births are associated with a higher rate of health problems, often because the babies are born prematurely and are smaller than normal.
How long is sperm kept in storage?
Normally in the UK it is only stored for 10 years, but there is scope to keep it for longer under special circumstances - such as developing testicular cancer at a young age.
Sperm must be destroyed once a man reaches the age of 55.
The Human Fertilisation and Embryology Authority, which regulates IVF in the UK, is currently reviewing the rules in this area.
Do many men use their frozen sperm?
A recent study revealed that only 27% of men who stored sperm at a Manchester centre before cancer treatent used their samples within 10 years.
Will new rules about IVF on the NHS have an impact?
Under new plans set out by Health Secretary John Reid, each couple will only be guaranteed one cycle of IVF treatment on the NHS, provided they have been trying for a baby for at least two years, and the woman is aged 23-39.
The National Institute of Clinical Excellence had recommended three free cycles.