LAUSR

Pain reliever use has been associated with both lower and higher risks of adverse reproductive outcomes in animals. The sole investigation of male pain reliever use and fertility in humans reported a 35% reduction in fecundability among men with urinary acetaminophen concentrations in the highest (>73.5 ng/ml) vs. lowest (<5.4 ng/ml) quartile. We analyzed data from 1,956 men participating in Pregnancy Study Online, a preconception cohort of North American couples enrolled between 2013 and 2019. Men and women completed baseline questionnaires on socio-demographics, lifestyle, medication use, and medical history; women completed bimonthly follow-up questionnaires for up to 12 months. We categorized pain medication by active ingredient (ibuprofen, acetaminophen, naproxen, aspirin) and cumulative monthly dose. We used proportional probabilities models to calculate fecundability ratios and 95% confidence intervals (CIs), adjusting for potential confounders. In the four weeks before baseline, 51.7% of men used pain medications. Adjusted fecundability ratios were 1.02 for ibuprofen (95% CI: 0.91, 1.13), 0.89 for acetaminophen (95% CI: 0.77, 1.03), 1.07 for naproxen (95% CI: 0.85, 1.35), and 1.05 for aspirin (95% CI: 0.81, 1.35), compared with non-use of each medication. In this study, male use of pain medications at low doses was not notably associated with fecundability.