Stressed women 'less likely to get pregnant'

While women have long been told to relax when trying for a baby, the evidence behind such claims has largely been anecdotal.

Now, scientists from Oxford University have shown the importance of relaxation when it comes to falling pregnant.

They carried out saliva tests on 274 women and analysed levels of the stress hormone cortisol and the enzyme alpha-amylase (an indicator of adrenalin levels).

All the women were aged between 18 and 40 and were trying for a baby naturally. None had been trying for more than three cycles before the start of the study and had not undergone fertility treatment.

Researchers carried out the tests on day six of each woman's menstrual cycle for a total of six cycles or until the woman fell pregnant.

They used fertility monitors to identify ovulation and confirmed the pregnancies with testing kits.

The study, published in the journal Fertility and Sterility, found no effect from cortisol on the chances of falling pregnant.

But women in the group with the highest levels of alpha-amylase had a 12 per cent lower chance of falling pregnant for each day of their most fertile days than those with the lowest levels of alpha-amylase.

The authors concluded: "Stress significantly reduced the probability of conception each day during the fertile window."