(HealthDay News) — Higher levels of stress as measured by salivary amylase levels are associated with reduced fecundity and increased risk of infertility, according to research published in online March 23 in Human Reproduction.

Courtney D. Lynch, PhD, MPH, of The Ohio State University College of Medicine in Columbus, and colleagues analyzed data for 401 couples who completed a prospective cohort study that investigated whether stress levels affected fecundity and fertility in women. Couples were followed for up to 12 months as they attempted to conceive; complete data for the analysis was available for 373 couples.

The researchers found that 347 of 401 couples (87%) became pregnant. After adjustment for female age; race; income; and use of alcohol, caffeine, and cigarettes while trying to conceive, women in the highest tertile of salivary alpha-amylase levels, compared with those in the lowest tertile, had a 29% decrease in fecundity as indicated by longer time-to-pregnancy (fecundability odds ratio, 0.71; 95% confidence interval [CI]. 0.51–1.00; P<0.05) and a more than two-fold increased risk of infertility (relative risk, 2.07; 95% CI, 1.04–4.11). No association was found between salivary cortisol levels and fecundability.

“This is the first U.S. study to demonstrate a prospective association between salivary stress biomarkers and time-to-pregnancy, and the first in the world to observe an association with infertility,” the authors write.

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