Women should not worry about using sperm from older donors as the success rate is the same as using a younger man's sperm, researchers say.
The average age of donors has risen in the UK since the right to anonymity was removed in 2005.
Doctors said there was concern about the impact on the odds of a pregnancy.
Experts said only older men with the best sperm could donate, so men as a whole should not see the results as an excuse to delay fatherhood.
A presentation at the European Society of Human Reproduction and Embryology annual conference showed the average age of donors was 26 before the law change and 34 afterwards.
"It is a huge difference," said Dr Meenakshi Choudhary from the Newcastle Fertility Centre.
"It may concern women, who are already older, who know their chances are lower, that if they go for an older sperm then their chance of a live birth will be further reduced and compromised."