London: High stress levels can delay pregnancy, a scientific study has found.
Researchers at Oxford University measured stress hormones in women planning a baby naturally and found the most stressed had a reduced chance of becoming pregnant.
The study followed 274 healthy women aged 18-40 planning a pregnancy.
Age, smoking, obesity and alcohol are known to affect pregnancy success, but the influence of stress is less clear.
Markers for two stress hormones - adrenalin, the body``s fight or flight hormone, and cortisol, connected with chronic stress - were measured in saliva.
The results showed that women with the highest levels of alpha-amylase (an indicator of adrenalin levels) had about a 12 percent reduced chance of getting pregnant during their fertile days that month compared with those with the lowest levels of the marker.
No difference in the chance of becoming pregnant was found with cortisol.
Anecdotal reports have long linked stress with infertility, but direct scientific evidence has been hard to find.
Dr Cecilia Pyper, of the National Perinatal Epidemiology Unit at the University of Oxford, said their study aimed to improve understanding of the factors that influence pregnancy in normal healthy women.
“This is the first study to find that a biological measure of stress is associated with a woman`s chances of becoming pregnant that month,” the BBC quoted her as saying.
"The findings support the idea that couples should aim to stay as relaxed as they can about trying for a baby.
"In some people`s cases, it might be relevant to look at relaxation techniques, counselling and even approaches like yoga and meditation," she added.
The study has been published in the journal Fertility and Sterility.