Impacts of Abstinence Time on Semen Parameters in a Large Population-based Cohort of Subfertile Men

OBJECTIVE To assess the effects of abstinence time on semen parameters in normozoospermic and oligozoospermic men using a large cohort of subfertile men. MATERIALS AND METHODS From 2002 to 2013, we retrospectively reviewed data from 15,623 patients seen at our fertility clinic. Data on patient age and semen parameters were extracted along with abstinence time. Abstinence time was categorized into 4 groups (<= 2 days; >2 and <= 5 days; >5 and <= 7 days; and >7 days). Semen samples were further categorized as normozoospermic or oligozoospermic based on concentration. Age-adjusted linear mixed effect regression models were used to test the effect of abstinence categories on semen parameters. RESULTS Data from 11,782 encounters (10,095 patients) were used for the final analysis after excluding patients <18 years old, azoospermic samples, and those missing all semen parameters. Mean age was 32.4 (standard deviation: 6.5) and median abstinence time was 4.0 days. There were 9840 normozoospermic and 1939 oligozoospermic samples. In normozoospermic men, longer abstinence was associated with increases in ejaculate volume, concentration, total sperm count, and total motile sperm count. However, in oligozoospermic men, longer abstinence time was not associated with improvements in semen parameters except ejaculate volume. CONCLUSION The effects of abstinence are different on semen parameters in normozoospermic and oligozoospermic patients. Longer abstinence does not improve most semen parameters in oligozoospermic samples. The World Health Organization recommendations for 2-7 days of abstinence may not be beneficial for subfertile patients when timing is a factor. (C) 2017 Elsevier Inc.