Men who feel under pressure to father a child often turn to another woman to fulfill their sexual needs, according to recent research.
Rigorous timing of sex sessions to take advantage of their partner's most fertile period, along with a high expectation to perform, can send some men running for the door.
One in 10 men are even likely to have an affair, say researchers who conducted their study in South Korea.
Questioning 400 men about their experience of trying for a baby with their long term partner, researchers found that men felt major performance pressure and at times struggled with impotence during, even with no history of sexual dysfunction.
The finding is consistent with previous research which found that testosterone levels in men and consequently libido declines during periods of major stress.
"It is clear that the greater instances of timed intercourse trials, the more incidences of erectile dysfunction and extramarital sex and the greater the desire to avoid sex with the intended partner," the authors observed in their study published in the Journal Of Andrology.
Higher levels of the stress hormone cortisol could be to blame for lowered testosterone levels typically seen in men under pressure.
Allan Pacey, professor of andrology at the University of Sheffield, told the Daily Mail: "While it is useful for couples to be aware of the fertile window, obsessing about it is not helpful at all."
Pacey suggests that regular sex with the aim to conceive is far more successful and less pressurised than waiting for the ovulation period.