By Michelle Roberts
Health reporter, BBC News in Lyon
Stressed-out African naked mole-rats may provide clues about infertility in humans, researchers believe.
Only the "queen" mole-rat reproduces
Dr Chris Faulkes of the University of London found stress blocked ovulation in female rodents and lowered the sperm count of males.
Although it is a big leap from mole-rats to humans, a fertility conference in Lyon heard how the animals provide a good study model.
Indeed, past work found stress-busting therapy restored fertility in women.
US researchers at Emory University in Atlanta, Georgia, discovered cognitive behaviour therapy alone was enough to help some women regain their periods.
Experts know that high levels of stress in women can change hormone levels and cause irregular ovulation.
Some studies have shown that high stress levels may also cause fallopian tube spasm in women and decreased sperm production in men.
And difficulty trying to conceive can, in itself, cause stress, leading to a vicious circle.
Anecdotal evidence shows that some couples who initially struggle to conceive and have a child by IVF or adoption, later fall pregnant naturally - possibly because the stress of the situation has been lifted.
Dr Faulkes and colleagues believe that a better understanding of what is going on in naked mole-rats could lead to a better understanding of the mechanisms involved in some stress-related infertility in humans and other mammals.
These tiny, blind, hairless subterranean rodents live in social colonies of 100-300 animals in the harsh, semi-arid conditions of Africa.
Only the "queen" mole-rat reproduces, suppressing fertility in both the females and the males around her by bullying them.
The advantage is that almost all the members of the colony can direct their energies towards foraging for food in order for the whole community to survive, rather than indulging in physically exhausting mating and reproductive behaviour.
Lessons from animals
Speaking at the European Society of Human Reproduction and Embryology (ESHRE) meeting Dr Faulkes said: "Social suppression of reproduction in marmoset monkeys is very similar to that in naked mole-rats, and as these are primates the applications to understanding human stress-related infertility aren't so far fetched.
"In humans, we know that various kinds of stress - physical and psychological - can affect fertility."
Clare Brown of Infertility Network UK said stress might exacerbate fertility problems.
"There is no doubt that both being diagnosed with fertility problems as well as undergoing fertility treatment is incredibly stressful.
"It is important that we look at all factors which might affect fertility and possibly impact on the success of any treatment. More research is required on this particular aspect.
"In the meantime, being in touch with patient organisations and having adequate access to counselling can help patients cope with stress."