BioEd Online

A combination of stress, dieting and exercise can dramatically affect female fertility, research on monkeys suggests. Although stress is known to reduce fertility, researchers now warn that if a woman is also dieting and exercising, the effect could be many times greater.

In stressed women, increased levels of a hormone called cortisol block the signal from the brain that tells the ovaries to release eggs, explain Sarah Berga and her colleagues at Emory University School of Medicine in Atlanta, Georgia.

In severe cases, a woman can stop producing eggs altogether and have her periods cease — a condition called amenorrhoea. About 5-10% of women suffer from amenorrhoea and Berga has previously found that giving such women behavioural therapy to control stress levels can help restore periods and fertility, without the need for specific fertility treatment¹.

Amenorrhoea is also caused by severe dieting and exercise, so to find out how these factors interact, Berga subjected a group of female monkeys either to mild stress (by putting them in a different room each day), or to a regime of calorie-restricted diet and exercise. The team presents its findings at the annual meeting of the European Society of Human Reproduction and Embryology (ESHRE) in Prague.

Potent mix

In each group, 10% of the monkeys stopped having periods. But when the monkeys were subjected to stress as well as diet and exercise, 75% of them stopped having periods.

Berga says the results show that women hoping to conceive should be particularly careful about dieting and exercising when stressed. "A little of each was much worse than a little of one," she says. "They feed off each other."

Having periods stop altogether is relatively rare, but Berga believes that stress levels could be affecting fertility to a lesser extent in many women. She is now starting a study that will track daily hormone levels in the urine of around 3,000 US nurses over the course of a year, to see how many of them have menstrual cycles disturbed by tension.

Researchers are also seeking clear evidence to show whether reducing stress can improve a woman's chances of getting pregnant during fertility treatment. Studies looking at stress in women undergoing IVF have so far been quite small. But Bea Lintsen of Radboud University Nijmegen Medical Centre in The Netherlands and her colleagues presented to the Prague meeting the results of a larger study, involving 1,088 women.

The researchers gave the women questionnaires about their anxiety levels while they were on the waiting list for treatment, and again one day before their eggs were collected. They conclude that stress didn't significantly affect the women's chances of conceiving. "We did not find a relationship between psychological stress and IVF outcome," they told the meeting. "Women who are concerned that their stress might harm their chances of conceiving can be reassured." This study, however, did not look at the additional effects of dieting and exercise.

Clowning around

However a unique study from Israel suggests that at a key time immediately after IVF treatment, using humour to lighten stress levels temporarily might improve the success rate. Shevach Friedler of the Assaf Harofeh Medical Centre in Zerifin is a graduate of the Jacques Lecoq school of mime and theatre in Paris. "My background is in clowning and movement," he says. "I'm also a physician who works in IVF. I thought we could combine the two."

He decided to employ a clown to entertain his patients as they recovered from their treatment. "After embryo transfer, stress could be critical, so we think this is a good time to use clowning to relax them," he says. "Everybody knows that humour is an effective way to reduce stress."

Over ten months, 93 patients aged between 25 and 40 were treated to the clown's performance for 10-15 minutes, shortly after their embryo transfer. Some 36% of them conceived, compared with just 19% in a group who didn't see the clown.

Worried that sophisticated adults might not find a traditional clown amusing, Friedler came up with a comedy chef character who offered the women steak and chocolate cake. "A clown with a red nose is fine for children, but we had to invent a new character for these adult women," he reflects. "The point is to get the women to smile and laugh."

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