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Urinary acetaminophen may indicate impaired fertility in men
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Couples whose male partner had higher urinary acetaminophen concentrations were more likely to experience a longer time to pregnancy or remain nonpregnant vs. couples whose male partner had lower urinary acetaminophen concentrations, recent study findings suggest.
“At this point, our findings need to be corroborated by future research, and there is no cause for alarm,” Melissa Smarr, PhD, a postdoctoral fellow in the division of intramural population health research at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Development, said in a press release.
Smarr and colleagues analyzed data from 501 couples of reproductive age without a diagnosis of infertility enrolled in the Longitudinal Investigation of Fertility and the Environment (LIFE) study. Participants, all recruited from 16 counties in Michigan and Texas between 2005 and 2009, discontinued using contraception for at least 2 months before enrollment. Couples provided a nonfasting urine sample from each partner after completing a baseline interview and completed daily journals to capture various lifestyle behaviors related to fecundity and sexual intercourse; women’s journals also recorded menstruation and pregnancy test results. Researchers followed couples until pregnancy or 1 year of trying to conceive.
Within 1-year follow-up, 347 couples (69%) had a human chorionic gonadotropin (hCG)-confirmed pregnancy, with 90% occurring within six menstrual cycles. Researchers found that urinary concentrations of acetaminophen were lowest among men and women who achieved pregnancy; p-aminophenol concentrations were lowest among those who did not achieve pregnancy.
In partner-specific models, men in the highest quartile of urinary acetaminophen concentration (at least 73.5 ng/mL) were more likely to experience delayed time to pregnancy vs. men in the lowest quartile (less than 5.44 ng/mL), after adjustment for age, BMI, creatinine, smoking status, race and income; the fecundability OR for men in the highest quartile was 0.67 (95% CI, 0.47-0.95); OR fell slightly after adjustment for hypertension and hypothyroidism (fecundability OR = 0.65; 95% CI, 0.45-0.92). Researchers observed no association between urinary acetaminophen concentrations in women and time to pregnancy.
“Nonetheless, the fourth quartile of male partners’ urinary [acetaminophen] was associated with delayed [time to pregnancy] in the adjusted couple-based models (adjusted fecundability OR = 0.65; 95% CI, 0.47-0.98),” the researchers wrote. “No associations were observed when couples’ urinary biomarkers were modeled continuously.”
Past research has suggested that acetaminophen may have endocrine-disrupting properties, according to study background. Smarr said in the release that the high urinary acetaminophen concentrations in some of the men in the study were more likely to be the result of environmental exposure to the chemical or to aniline, a precursor compound used to in many common product.
The researchers noted that residual confounding by indication of medication use or the potential for chance findings cannot be ruled out, and the exploratory findings support the need for future studies to consider both partners’ exposures when assessing couple-dependent outcomes, including time-to-pregnancy. – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.
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