BACKGROUND

Paternal age association with sperm parameters has been previously studied, demonstrating a decrease in semen volume, sperm motility, and sperm morphology, but not in sperm concentration. However, scarce data exists on the individual intra-personal changes in semen parameters with time.

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To evaluate the changes in semen parameters and total motile count of infertile men over time.

MATERIALS AND METHODS

In this retrospective cohort study, infertile men without known risk factors for sperm quality deterioration and at least two semen analyses done > 3 months apart, between 2005 and 2021, were evaluated. Allocation to groups was according to time between first and last semen analyses - 3-12 months, 1-3 years, 3-5 years, and > 5 years. Basic characteristics and first and last semen analyses were compared. The primary outcome was the change in sperm parameters and the secondary outcome was the occurrence of a total motile count < 5 million in men with an initial total motile count > 10 million.

RESULTS

A total of 2018 men were included in the study. The median age at first semen analyses was 36.2 (interquartile range: 32.8-40.1) years and the median time between semen analyses was 323 days (range 90-5810 days). The overall trend demonstrated an increase in concentration in the 3-12 months and the 1-3 years groups, whereas volume, motility, and morphology remained similar in these time groups. Semen analyses done more than 5 years apart showed decreased volume (p < 0.05), motility (p < 0.05) morphology (p < 0.05), and steady sperm concentration. Significant declines in TMCs were found over time (p < 0.001), with 18% and 22% of infertile men with an initial total motile count > 10 million dropping to < 5 million after 3 and 5 years, respectively. The factors independently predictive of total motile count < 5 M in the last semen analyses in men with an initial total motile count of > 10 M in a multivariate logistic regression model were baseline volume (odds ratio 0.80, p = 0.03), baseline total motile count (odds ratio 0.98, p = 0.01) and time between semen analyses - 3-5 years (odds ratio 3.79, p < 0.001) and > 5 years (odds ratio 3.49, p = 0.04) DISCUSSION: Our study demonstrates, at the individual level, that while improvement in sperm concentration is observed in the first year and between 1 and 3 years, possibly due to fertility treatments, fertility-related counseling, and lifestyle changes, semen parameters decline with time over 3 years in individuals. Of significance, close to 22% of men with an initial total motile count > 10 million (a range where spontaneous pregnancy is attainable) declined to < 5 million (a range usually indicating a need for in-vitro fertilization/intracytoplasmic sperm injection) over 5 years. This data could contribute to individualized family planning for infertile men regarding the mode and timing of conception and the need for sperm banking, in order to minimize the need for future fertility treatments.