Self-Reported Asthma Is Associated with Reduced Sperm Count-A Cross-Sectional Study of More than 6000 Young Men from the General Population

Asthma is driven by an inflammatory response that may impact testicular function. In this cross-sectional study, we investigated the association between self-reported asthma and testicular function (semen parameters, reproductive hormone levels), and determined whether potential further inflammation due to self-reported allergy modified this association. A total of 6177 men from the general population completed a questionnaire including information on doctor-diagnosed asthma or allergy, had a physical examination, delivered a semen sample, and had a blood sample drawn. Multiple linear regression analyses were performed. A total of 656 (10.6%) men reported having ever been diagnosed with asthma. Generally, self-reported asthma was consistently associated with a poorer testicular function; however, few estimates were statistically significant. Specifically, self-reported asthma was associated with statistically significant lower total sperm count [median: 133 vs. 145 million; adjusted beta (95% CI): -0.18 (-0.33 to -0.04) million on cubic-root-transformed scale] and borderline statistically significant lower sperm concentration compared with no self-reported asthma. The association between asthma and total sperm count was of similar magnitude among men with and without allergy. In conclusion, men with self-reported asthma had poorer testicular function than men without asthma. However, the cross-sectional design of the study limits ascertainment of causality.