A new study from researchers at the National Institute of Health and the University of Oxford supports that belief.
Researchers examined women who did not have a history of fertility problems and found a link between the stress levels found in a saliva enzyme and their chance of conception.
Alpha-amylase is an enzyme in the saliva that digests starch, but recently, some scientists have used it as an indicator of the body's response to stress. In the study, women who had higher levels of the enzyme were less likely to get pregnant than women with lower levels.
Researchers charted the ovulation cycles of 274 women, and collected saliva samples that were tested for the enzyme.
They found that the 25 percent of women who had the highest enzyme levels had an estimated 12 percent reduction in getting pregnant compared to the women with the lowest enzyme levels.
Rather than turning to alcohol or tobacco which also lower the chance of pregnancy, women should try relaxation techniques such as meditation or yoga to curb stress. A new study with a larger group of women is currently going on to confirm the findings.