Sports players and fans are being targeted in a campaign to get more sperm donors to help couples struggling to conceive.
The National Gamete Donation Trust wants to increase the number of new donors in the UK to about 500, from its latest figure of 384.
Leaflets and posters are being sent to 30 sports clubs and venues in the pilot area of Greater Manchester. One in six couples in the UK struggles to conceive and some areas have waiting lists for those who need donor sperm.
In the UK there are hundreds of couples who need a sperm donor to help them conceive the child they long for so much, either because of infertility or genetic disease
Laura Witjens, from the National Gamete Donation Trust It is hoped that the sports theme of the posters will encourage more men to come forward.
One says: "Strong swimmers wanted" and another encourages volunteers with "Whatever your shape and size, couples need your help".
The number of new sperm donors dipped in the UK in 2004 to 224. The law changed in 2005, meaning egg and sperm donors did not have the right to anonymity.
But since then the number of new donors has increased with 384 registering in 2008.
The children of donors can trace their biological parents when they reach 18.
Donors are not paid, but can claim expenses.
Laura Witjens, chairwoman of the National Gamete Donation Trust, said: "In the UK there are hundreds of couples who need a sperm donor to help them conceive the child they long for so much, either because of infertility or genetic disease.
"These couples rely on men stepping forward as sperm donors."
In the latest figures from 2006, there were 5,000 cycles of fertility treatment in the UK which used donor sperm.
Pride Angel parenting website connection service aims as helping lesbian couples, single women and infertile couples achieve parenthood. Sperm donors and co-parents are able to donate directly to the woman or couple of their choice.
Members communicate safely by means of an internal messaging system to find their suitable match. Pride Angel also provides information on health screening, artificial insemination and legal rights with fertility law specialists giving advice through the Pride Angel Forum.
Read more about helping women and donating sperm directly at www.prideangel.com