Women with the highest levels of alpha-amylase, a biomarker of stress, when they were trying to conceive were nearly one-third less likely to conceive than their less-stressed peers, and twice as likely to meet the clinical definition of infertility, according to a prospective cohort study.
Courtney Denning-Johnson Lynch, PhD, director of reproductive epidemiology at the Ohio State University Wexner Medical Center, Columbus, and colleagues published their findings online March 23 in Human Reproduction.
According to published literature, stress and reproduction are linked, but gaps remain in knowledge about infertility, Dr. Lynch and colleagues write. Whereas high-tech assisted reproduction techniques can help, some of the hefty price tag could be avoided if couples knew more about simple, inexpensive lifestyle changes that could up their odds of conceiving.
From 2005 to 2009, the researchers enrolled 501 couples they identified through a marketing and fish/hunting license registry in 16 counties in Michigan and Texas and followed them as they tried to conceive for up to 12 months or through pregnancy. The women were aged 18 to 40 years, and their male partners were at least 18 years old. Of 401 women who completed the protocol, 373 women had complete saliva data for analysis and 347 women became pregnant.
Of the 75 women with complete saliva data who withdrew from the study, 52 were non-Hispanic white women, 10 were Hispanic, and 8 were non-Hispanic black women. Women who became pregnant were more likely to be higher educated, to have a higher family income, and to not smoke or to smoke less, according to the researchers.
In a multivariate analysis adjusted for female age, race, income, and use of alcohol, caffeine and cigarettes, the investigators found that women in the highest tertile for alpha-amylase, a protein enzyme that appears at elevated levels in saliva after chronic stress, were 29% less likely to conceive than those in the lowest tertile (odds ratio, 0.71; 95% confidence interval [CI], 0.51 - 1.00; P < 0.05). They were also more than twice as likely to meet the definition for infertility (relative risk, 2.07; 95% CI, 1.04 - 4.11).
In contrast, the investigators found no association between loss of fecundity and cortisol, another biomarker of stress.
"This work corroborates and extends our previous work in which we reported a prospective association between increased alpha-amylase and a 12% reduction in the day-specific probabilities of pregnancy in the first cycle among UK women," Dr. Lynch and colleagues write.
"One question that remains unanswered is the biologic mechanism by which stress might impact fecundity. In the current study, we found no differences in acts of intercourse during the fertile window between women who did and did not become pregnant, nor did we see a decreased coital frequency among women with the highest salivary alpha-amylase levels."
The authors argue that it "seems prudent" to consider the effect of stress for couples who fail to conceive despite 6 months of trying and suggest they consider yoga, meditation, and mindfulness as potential stress-busting activities.
"While one must be careful to avoid any potential 'blame', by pointing out that high levels of stress are clearly neither the only nor the most important factor predicting one's ability to get pregnant, the suggestion that a woman considers participating in an effort to reduce her stress level is certainly unlikely to cause harm," the authors conclude.
Support for this study was provided by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. The authors have disclosed no relevant financial relationships.
Hum Rep. Published online March 23, 2014. Full text
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Cite this: Stress Trims Conception Odds in Prospective, Biomarker Study - Medscape - Mar 24, 2014.