Better sperm storage method on the way

A team of scientists from Chile and Germany found that fast-freezing sperm preserves its ability to swim towards an egg far more efficiently than the slow-freezing method in use. The method, according to the scientists, also offers the chance to cancer patients and HIV-infected men to become fathers without passing on the disease to the newborn.

In the existing slow-freezing techniques, the sperm only retains 30 to 40 per cent of activity. But rapid freezing — also known as vitrification — allows that figure to rise to almost 80 per cent.

Vitrification is already used to quick-freeze eggs and embryos with success, allowing spare ones to be used in IVF at a later date. Following thawing, more eggs and embryos survive with vitrification than with older, slower cooling techniques.

Men with a low sperm count and whose sperm is deteriorating in quality over time would also benefit from the technique, they said.

Some men with low sperm counts fail to produce a good enough sample when it is time for IVF. The new technique could also allow several samples to be put together as one.