P–018 Observational study on the behaviour of the seminal sample in donors: seasonal variation according to parameters
Authors: Amoroch. Llanos B , Hernánde. Jornet R , Sellé. Soriano E , Martíne. Díaz-Jiménez E , Cano I.Pére , Muño. Cantero M 
Published: August 2021

Abstract

Study question
What is causing the decline in semen quality worldwide?

Summary answer
Our results indicated significant differences, finding a decrease in sperm concentration/mobility in summer compared to the other seasons, with greater differences being observed in spring.

What is known already
Infertility is an increasing global problem and it is estimated that approximately 15 to 20% of all couples experience it at some point in their reproductive life. Among all causes, the male factor is becoming increasingly important as seminal quality is steadily declining globally. Knowing that the spermatogenesis process is very sensible to temperature fluctuations we could focus on the ambient temperature as one of the causes.

Study design, size, duration
Taking into account that donors are selected for having an optimal seminal quality, a retrospective study (January 2006 /February 2020) was proposed at IVI Alicante from 160 seminal samples to determine whether environment actually affects spermatogenesis and semen quality. It was evaluated whether there is variation in donors in mobility/volume / concentration depending on the season and quarter of the year in which the sample was obtained; and relation to the age of the donor.

Participants/materials, setting, methods
The inclusion criteria were sperm donors between 18 and 35 years old, anonymously, with good physical health, full capacity to act, and with seminal samples with characteristics to survive sperm thawing, complying with the requirements according to Spanish law on ART 2006. Exclusion criteria were based mainly on poor sperm survival after thawing. The statistical analysis was performed with the R statistical software, version 4.0, linear and multiple regression, establishing significant differences when p &lt; 0.05.

Main results and the role of chance
The results indicated significant differences, finding in summer a decrease in concentration and sperm motility (p &lt; 0.05) compared to autumn and winter and obtaining the best quality in spring. The concentration and mobility decrease from 63.4 million sperm / ml and 49.6% in spring to 44.4 million (p = 0.009) and 39.9% mobility in summer (p = 0.0075). We found the same results comparing them by quarters, having 62.7 million / ml and 49.3% between April-June, up to 44.9 million (p = 0.003) and 39.3% mobility between July-September (p = 0.03), showing that July and September there is a decrease in both concentration and mobility. This association has not been significantly affected by age. Thus, we conclude that high temperatures affect seminal concentration and mobility.

Limitations, reasons for caution
More studies can be done to increase the number of donors and confirm our findings.
Wider implications of the findings: According to other studies, carried out in Denmark, Israel and China, with different latitudes and temperature-humidity, the same trend has been observed in sperm quality, decreasing the quality in summer and being optimal in spring-winter, so the temperature could be a variable to take into account when studying semen.

Trial registration number
Not applicable for non clinical-trials