Women with higher levels of stress may be twice as likely as others to experience long-term infertility.

In a new study, researchers from Ohio State University found that women with higher levels of alpha-amylase — an established biomarker for stress — were 29 percent less likely to get pregnant during any given month. Over time, women undergoing the highest levels of stress were about twice as likely as others to be considered clinically infertile.

As part of a long-term study, the researchers analyzed data from a longitudinal study of 500 American women of childbearing age — ranging from 18 to 40 — who had been experiencing trouble with infertility. With samples from 373 of the women in the study, the researchers tested for the protein biomarker as well as for the stress hormone cortisol.

"This is now the second study in which we have demonstrated that women with high levels of the stress biomarker salivary alpha-amylase have a lower probability of becoming pregnant, compared to women with low levels of this biomarker,” study leader Courtney Denning-Johnson Lynch, director of reproductive epidemiology at the university’s medical center, said in a statement. “For the first time, we've shown that this effect is potentially clinically meaningful, as it's associated with a greater than two-fold increased risk of infertility among these women.”

Researchers have found that the more stress women are under while trying to get pregnant, the harder it is. While Abigail David and her husband were trying to conceive, the stress of working full time and trying to start a business may have delayed Abigail's pregnancy. A new study led by researchers at the Ohio State University Wexner Medical Center found that women who were found to have high levels of a stress biomarker had a 29 percent decrease in the probability of getting pregnant and her risk of infertility doubled. Ohio State University

However, the researchers added that stress is only one factor influencing fertility, lest anxious mothers-to-be fear a self-fulfilling prophecy. Rather, Lynch said women feeling anxious about fertility problems should try yoga, meditation, and mindfulness to alleviate feelings of stress — and to refrain from blaming oneself.

Germaine Buck Louis, of the National Institute of Child Health and Human Development, led the longitudinal study that provided the data for Lynch’s study. "Eliminating stressors before trying to become pregnant might shorten the time couples need to become pregnant in comparison to ignoring stress,” he said in the statement. “The good news is that women most likely will know which stress reduction strategy works best for them, since a one-size-fits-all solution is not likely."

Yet although some women may eschew yoga and similar practices, scientists are quick to remind women they should not drink while trying to get pregnant.

Source: Human Reproduction. 2014.