Men are unaware that getting older, drinking too much and being obese can reduce their fertility, according to a new poll.
The survey found some men did not want to discuss fertility problems with their GP or partner, while many underestimated the proportion of fertility problems that are attributable to men.
Almost half (49%) of more than 2,000 men polled were not aware that sperm suffers more genetic faults as men get older.
More than one in three men were unaware that fertility decreases the more men drink, while 33% of men smoked regularly despite the fact smoking reduces sperm quality.
Almost half (46%) of men were also unaware that being overweight or obese meant it could take longer for couples to conceive.
Some 55% of men were also unaware that sexually-transmitted infections could affect their fertility.
The poll was carried out by Nuffield Health in partnership with the charity Infertility Network UK.
Helen Lyall, a consultant at Nuffield Health Glasgow Hospital, said: "From my experience, it is clear that men may be embarrassed to talk about fertility problems and it's generally women who make the first step towards addressing fertility concerns.
"However, with one in six couples facing fertility issues, it is important to reassure men that this is not a taboo subject and to take away the stigma around discussing fertility."
Of those men surveyed, almost a third said they had suffered fertility issues.
Almost 60% of these said it had negatively affected their relationship, one in three said it had hit their work life and 40% said it had an impact on their mental health.
Susan Seenan, chief executive of Infertility Network UK, said: "Men are half of the fertility equation - they experience the pain and grief of struggling to become parents too.
"However, the male perspective can be overlooked. The survey reveals that nearly half of all men feel there is not enough support and information for men about fertility issues and going forwards we hope to address this with men and their partners, as well as healthcare professionals."
In approximately 40% of infertile couples, the male partner is either the sole cause or a contributing cause of infertility.