Infertility among women may be linked to long-term stress, a new study suggests. Researchers from the Ohio State University Wexner Medical Center say that stress can reduce a woman's ability to conceive by as much as 29 percent.
The U.S. Centers for Disease Control and Prevention (CDC) reports that 6.7 million women have difficulty getting pregnant, representing 10.9 percent of women of reproductive age.
Researchers, led by the study's author Courtney Lynch, investigated 401 women ages 18 to 40 looking to conceive. They analyzed their saliva samples for levels of stress hormones, cortisol and alpha-amylase, twice -- at the beginning of the study and after the women's first menstrual cycles.
They then followed these women for a year, and observed that by five to six months into the study, the couples who had not yet conceived were those with the highest levels of chronic stress.
Women who had high levels of alpha-amylase took, on average, 29 percent longer to conceive compared to those with low levels of the stress biomarker. They also had more than two-fold greater risk of infertility.
"[People] think of 'fight or flight' as an acute response, but as time has gone on, folks have realized if you're experiencing chronic stress, lots and lots of acute stress, that 'fight or flight' [response] never turns off," Lynch told Fox News.
Lynch adds that the study's results, published in the journal Human Reproduction, do not prove that stress alone is the only reason why women can't get pregnant.
"The message is not that everyone should go enroll in yoga tomorrow," told WebMD. "The message is that if you've tried for five or six months and you aren't getting anywhere, maybe you should look at your lifestyle and think about whether or not stress might be a problem for you. And if it is, you might want to consider a stress-management program."
According to the American Society of Reproductive Medicine, chronic stress increases the production of certain hormones in the body that can either delay or completely skip the time a woman releases an egg. The site also adds that, surprisingly, many women treated for infertility have as much stress as women diagnosed with cancer or heart disease.
"[Lowering stress] ensures people have as healthy and as productive a life as they're able to have," Lynch concluded.
