Stress plays an important role in reproductive health and likely is one of the psychological factors affecting ART success. This study was designed to examine the relationship between the stress level as inferred from the amount of the enzyme alpha-amylase secreted in saliva (SAA) and pregnancy outcome in infertile couples undergoing in vitro fertilization and embryo transplantation (IVF-ET). A prospective cohort study was conducted in the Reproductive Medicine Centre of Zhengzhou University Hospital in Henan, China. Four hundred fifty-seven infertile couples undergoing in vitro fertilization and embryo transplantation (IVF-ET) for the first time participated in the study. Couples collected saliva samples the morning before the start of their first treatment cycle for the measurement of SAA. We found that the level of SAA (and hence, the amount of stress) in female partners, male partners, and couples analyzed together significantly affected IVF-ET outcome. Cutoff levels of SAA that predicted pregnancy failure were 136 μmol/L, 149 μmol/L, and 288 μmol/L in female partners, male partners, and couples, respectively. Female partners, male partners, and couples with high SAA levels had increased risk of pregnancy failure compared to those with low SAA levels. The SAA level directly correlated with the follicle-stimulating hormone level and was inversely proportional to the anti-Müllerian hormone level and endometrial thickness. Some semen parameters of male partners, such as density, survival rate, sperm rapid progressive motility (A%), and progressive motility [(A + B)%], were significantly lower in the high-SAA than in the low-SAA group. Furthermore, couples in the high SAA group had fewer transferable and high-quality embryos. We concluded that a high SAA level, known to be an objective indicator of high stress, increases the risk of pregnancy failure in infertile couples undergoing IVF-ET. Lay summary To explore the relationship between stress, as measured by the levels of the stress biomarker salivary alpha-amylase (SAA), and pregnancy outcome in infertile couples undergoing in vitro fertilization, a prospective cohort study was conducted in the Reproductive Medicine Centre of Zhengzhou University Hospital in Henan, China. Four hundred fifty-seven infertile couples undergoing IVF-ET collected saliva samples the morning before the start of their first treatment cycle for the measurement of SAA. Results of this study demonstrated that a high SAA level, known to be an objective indicator of high stress, increases the risk of pregnancy failure in infertile couples undergoing IVF-ET.
Keywords: fertilization; Female infertility; male infertility; stress.