Being stressed about IVF treatment does not reduce a woman's chance of it being successful, a study suggests.
Going through IVF can put a strain on a relationship
Many women having fertility treatment feel anxious about the outcome.
But Swedish researchers surveyed 166 women a month before they underwent IVF treatment and found no link between their stress and the eventual outcome.
Writing in Human Reproduction, they said they hoped their findings would comfort women, and even help reduce their stress levels.
Previous studies examining the effect of stress on IVF have reached conflicting conclusions.
The team from the University of Gothenburg carried out a predictive study to look at the effect.
One hundred and sixty-six women completed a recognised health questionnaire to evaluate their psychological state a month before undergoing their first cycle of IVF treatment.
Participants completed another just prior to their eggs being retrieved for the IVF procedure.
A total of 139 women had viable embryos available for transfer - 58 conceived and 81 did not.
When researchers looked back at the pre-treatment questionnaires, they found the results did not differ between those who became pregnant and those who did not.
There was also no difference on an additional test which had been given to patients prior to IVF, that was designed specifically to assess 14 emotions often expressed by infertility patients.
Dr Lisbeth Anderheim, of the Department of Obstetrics and Gynaecology at Sahlgrenska University, who led the research, said: "We can use these findings to reassure women and this information should, in itself, help to reduce their stress and worry levels."
She said it was possible patients were keeping worries to themselves because they had great expectations and were giving answers that were more positive than they felt.
It may also have been valuable to question patients at the point the embryos were transferred, which is known to be a time of heightened tension, she said.
But Dr Anderheim said the fact that it was impossible to establish a link in a prospective study between stress and the chances of conceiving via IVF was encouraging.
"During IVF treatment patients frequently ask about the relationship between psychological stress and outcome and often express worries that their own stress might have a negative influence, so the fact that our prospective study did not indicate any relationship is reassuring.
"This is a positive message we can give our patients to help decrease their stress at this time."
Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield, said: "Undergoing IVF is stressful enough. It is reassuring to know that a couples' stress levels are not going to lower their chances of success."
But a spokeswoman for Infertility Network UK said: "Stress may not be a significant factor in the outcome of treatment, but it is a very real factor throughout the infertility process and affects every part of a couples life.
"We often find that couples will only speak of their anxieties to each other or others who have experienced similar problems.
"Infertility Network UK gives them the opportunity to speak to others through our helplines, local groups and chatrooms and forums."