Urine cortisol concentration as a biomarker of stress is unrelated to IVF outcomes in women and men

Purpose Our primary objective was to assess associations between urine cortisol as a biomarker of psychological stress and in vitro fertilization (IVF) outcomes. A secondary objective was to assess associations between toxic metals and cortisol. Methods Urine and blood specimens were collected from 52 women and 28 male partners completing a first IVF procedure, on the day of oocyte retrieval. Urine cortisol was measured with an enzyme-linked immunosorbent assay. Mercury (Hg), cadmium (Cd), and lead (Pb) were determined in blood and Cd in urine by inductively coupled plasma-mass spectrometry. Results No associations were indicated for cortisol with IVF outcomes in multivariable regression models adjusted for covariates. However, we detected positive linear associations for cortisol and urine Cd (beta=9.96, 95% CI 1.52, 21.44) and blood Hg (beta=1.44, 95% CI 0.31, 3.18). An exploratory stratified analysis suggested a potential inverse association between urine cortisol and oocyte fertilization among women with low, but not high blood Hg. Conclusion While limited, these preliminary data suggest that psychological stress may not play a major role in IVF outcomes, which therefore could be one less concern for couples and their clinicians. Our data also raise the possibility for toxic metals to modify associations between cortisol and IVF outcomes among women. However, these preliminary results require corroboration in an experimental animal model and confirmation in a larger, more definitive observational study.