If you've been trying to conceive for a while and not having much luck, then stress might be the cause.
Researchers in Ohio State University Wexner Medical Center, in Columbus, Ohio, studied 510 couples aged 18-40 with no known medical problems. They found that in that group, women with high levels of a hormone called alpha-amylase, caused by stress, were twice as likely to be unable to conceive for more than a year.
The hormone is linked to adrenaline which is produced by the body in a 'fight or flight' situation.
Women who are unable to conceive after 1 year of unprotected sex are considered to be clinically 'infertile'.
Stress-reduction has long been recommended to couples having problems conceiving and this study provides actual evidence of how important lack of stress is in conception. Relaxation and exercise classes such as yoga and pilates are recommended, as are alternative therapies reflexology and acupuncture. But above all, try and relax because the more you get stressed about not getting pregnant, the harder it will be.
There are many other reasons why women are unable to get pregnant and if you've been trying unsuccessfully for more than a year, then visit your GP, who can refer you for tests and further investigations.