Sperm donors up to the age of 45 are just as likely to conceive children as those in their 20s, new research led by Indian-origin doctors has found.

Despite emerging evidence of a decline in sperm quality with increasing age, an analysis of every first fertility treatment cycle performed in the UK using sperm donation shows that outcome in terms of live birth is not affected by the age of the sperm donor.

Results from the study, said its principal investigator Dr Meenakshi Choudhary, from the Newcastle Fertility Centre at Life, UK, reaffirm the observation that a couple's fertility appears significantly more dependent on the age of the female partner than on that of the male.

From a total of more than 230,000 sperm donation cycles in the study, 39,282 were from a first cycle of treatment (with either IVF or donor insemination) and were included in the analysis.

With the assumption that female fertility clearly declines with age, the study divided its female subjects into two groups: those who were treated with donor sperm between the ages of 18 and 34, and those who were treated after the age of 37.

Researchers found live birth rate from IVF with donated sperm was around 29 per cent in the 18-34 age group, but only around 14 per cent in the over-37 age group.

However, within these same two female age bands, no significant differences were found in live birth rate (LBR) relative to the age of sperm donor.

In the younger IVF patients LBR was 28.3 per cent with a sperm donor aged under 20 and 30.4 per cent with a donor aged 41-45 while as in the younger donor insemination patients LBR was 9.7 per cent with a donor aged under 20 and 12 per cent with a donor aged 41-45.

There was a trend, for example, that sperm donors under the age of 20 were associated with a less successful outcome than older donors.

In the older IVF patients LBR was 11 per cent with a donor under the age of 20, 17 per cent with donor aged 26-30, and 16.6 per cent with a donor aged 41-45, while as in the older donor insemination patients LBR was 3.1 per cent with a donor under 20, and 4.6 per cent with a donor aged 41-45.

"Despite these trends, it's important to note that the impact of sperm donor age on live birth failed to reach statistical significance in any of the age groups we studied," said Choudhary.

"Our results suggest that, up to the age of 45, there is little effect of male age on treatment outcome, but sperm donors are a selected population based on good sperm quality.

"This confirms the view that a man's age doesn't matter in achieving a live birth provided his sperm quality is good," Choudhary said.

The results of the study were presented at the Annual Meeting of European Society of Human Reproduction and Embryology (ESHRE) in Munich by Choudhary's colleague, Commonwealth Clinical Fellow Dr Navdeep Ghuman.