Stress reduces conception probabilities across the fertile window: evidence in support of relaxation.
Level 3 - non-randomized controlled study
Prospective observational cohort study
PubMed 20688324 · doi:10.1016/j.fertnstert.2010.06.078
What was done
A prospective cohort study evaluated 274 women aged 18 to 40 in the United Kingdom who were attempting pregnancy. Participants were followed for up to six menstrual cycles or until pregnancy occurred. Basal saliva samples were collected on day 6 of each cycle to measure salivary cortisol (µg/dL) and alpha-amylase (U/mL). Ovulation was tracked with fertility monitors and pregnancy was confirmed with home test kits. Discrete-time survival analysis and Bayesian modeling assessed fecundity (time-to-pregnancy) and daily conception probability across the fertile window, adjusting for female and partner age, intercourse frequency, and alcohol intake.
What was found
Salivary alpha-amylase, but not cortisol, was negatively associated with fecundity in the first cycle (adjusted fecundity odds ratio = 0.85; 95% CI: 0.67 to 1.09). In Bayesian modeling, women with salivary alpha-amylase concentrations in the upper quartiles had a statistically significant reduction in daily conception probability across the fertile window during the first cycle compared to women in lower quartiles (highest posterior density: -0.284; 95% interval: -0.540 to -0.029).
Why it matters
This study provides prospective biomarker evidence that sympathetic nervous system activation, as indicated by salivary alpha-amylase, is associated with lower per-day conception probabilities during the fertile window.
Limits
The observational design cannot establish causality. Biomarkers were measured from a single basal saliva sample on day 6 of each cycle, which may not reflect stress levels throughout the entire fertile window or across subsequent cycles. The primary statistically significant finding was restricted to the first cycle of pregnancy attempts, and the 95% confidence interval for the overall fecundity odds ratio crossed 1.0. Other unmeasured lifestyle and reproductive confounders could not be excluded.
Cited by
- supports Research indicates that psychological stress makes it harder to conceive.