BackgroundObstructive sleep apnea (OSA) has several notable complications such as hypertension and diabetes. Studies have also shown that OSA is associated with erectile dysfunction and reduced androgen levels. However, the effect of OSA on semen quality remains poorly studied.MethodsMen attending a tertiary reproductive center for semen analysis were tested with a portable sleep breathing monitor. Patients were divided into four groups based on their apnea hypopnea index: none, mild, moderate, and severe obstructive sleep apnea. Differences between groups were assessed using chi 2, and associations were tested with multiple regression analysis.ResultsWe included a total of 175 male subjects with a mean age of 32.2 +/- 3.6 years. There were significant differences between groups in progressive sperm motility (%) (43 +/- 16, 42 +/- 17, 36 +/- 18, 29 +/- 18, respectively; p = 0.002), total motility (%) (59 +/- 19, 59 +/- 20, 49 +/- 21, 42 +/- 20, respectively; p = 0.010), and vitality (%) (80 +/- 10, 81 +/- 11, 79 +/- 8, 72 +/- 19, respectively; p = 0.039). Asthenospermia (progressive motility < 35%) was significantly more common in subjects with OSA (chi 2 = 5.195, p = 0.023). In multiple regression models, after adjusting for age and body mass index, apnea hypopnea index remained negatively and significantly associated with progressive motility, total motility, and vitality.ConclusionsOSA is an independent risk factor for sperm motility and vitality, and further investigation is now needed to determine if continuous positive pressure ventilation or other therapies can improve semen quality in these patients.