Study suggests stress link to fertility problems, but methodology questioned

A US study suggests that preconception stress is associated with lower levels of fertility in women attempting to conceive naturally. However, the study has several limitations and experts warn that worrying about the role of stress in fertility may in fact lower chances of conceiving.

The study, which was published in the journal Human Reproduction, found that women with higher levels of the stress hormone, alpha amylase, are less likely to conceive each month and are more than twice as likely to not get pregnant after 12 months of regular unprotected sex.

Dr Courtney Lynch, study lead author from Ohio State University, suggested that simple stress-reduction techniques may improve chances: 'We do know that there are things out there that are helpful in reducing women's stress. Things like meditation and yoga can help'.

The study obtained data from 401 US women who were trying to conceive for one year. If they became pregnant they were followed throughout pregnancy. The women were all aged between 18 and 40 and had no existing fertility problems.

The researchers assessed stress levels by measuring the levels of two stress hormones (alpha amylase and cortisol) in the saliva. Women gave samples of saliva the morning after they enrolled in the study and the morning after their first period during the study.

The results showed that women with the highest third of salivary alpha amylase levels had a 29 percent lower chance of becoming pregnant each month compared to women with the lowest levels of alpha amylase. However, this result was only of borderline statistical significance. The researchers also found that women with the highest levels of alpha amylase were twice as likely to fail to conceive over 12 months.

NHS Choices reports that there were several limitations to the study and that those trying to conceive 'should not be concerned by the results'. Salivary stress hormones were only measured on two occasions and so provide a limited assessment of daily levels of stress. There was also no significant difference between overall levels of salivary stress hormones in women who did and did not become pregnant.

In addition, the study showed no associations between the levels of the classic stress biomarker, cortisol, and either the likelihood of conceiving or the time it took to conceive. Importantly, the study fails to uncover whether increased stress leads to lower chances of conceiving or whether failure to conceive increases stress, writes NHS Choices.

Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield told the Daily Mail: 'At the present time there is no evidence that [relaxation therapies] will be of any help in increasing the probability of conception. However, they are unlikely to cause harm and they may be enjoyable and help with other aspects of life as well'.