Women who are stressed could find it harder to conceive a child.
This is according to a recent research project conducted by scientists at Oxford University.
The study looked at the levels of stress hormones in 274 women, aged between 18 and 40.
Those women who had the highest levels of alpha-amylase, an indicator of the stress hormone adrenaline, were found that have a 12 per cent lower chance of falling pregnant than those women with the lowest levels of the stress marker.
Dr Ceclilia Pyper, from the National Perinatal Epidemiology Unit at the university, commented: "We found that those women with high levels of a marker for stress were less likely to succeed in conceiving.
"The findings support the idea that couples should aim to stay as relaxed as they can about trying for a baby."
Fertility and Sterility published the research, which is part of a larger study looking at other factors affecting pregnancy.