Effects of environmental temperature extremes exposure on sperm quality - Evidence from a prospective cohort study in Anhui Province, China.

ABSTRACT

Extreme weather is becoming more frequent due to drastic changes in the climate. Despite this, the body of research focused on the association between temperature extreme events and sperm quality remains sparse. In this study, we elucidate the impact of exposure to environmental temperature extremes on sperm quality. Data for this investigation were derived from the Anhui Prospective Assisted Reproduction Cohort, encompassing the period from 2015 to 2020. Parameters such as sperm concentration, total sperm count, total motility, progressive motility, total motile sperm count, and progressive motile sperm count were quantified from semen samples. We assessed the exposure of participants to temperature extremes during the 0-90 days prior to sampling. This investigation encompassed 15,112 participants, yielding 28,267 semen samples. Our research findings indicate that exposure to low temperature extreme for three consecutive days (at the first percentile threshold) has a detrimental correlation with sperm count parameters and concentration. Similar trends were observed with the second percentile threshold, where significant adverse effects typically manifested after a four-day exposure sequence. Analysis of high temperature extreme showed that exposure at the 98th percentile had adverse effects on all six sperm quality parameters, and the sperm count parameter was particularly sensitive to high temperature, showing significant results immediately after three days of exposure. When considering even more temperature extreme (99th percentile), the negative consequences were more pronounced on the sperm count parameter. Additionally, progressive motility showed a stronger negative response. In summary, parameters associated with sperm count are particularly vulnerable to temperature extremes exposure. Exposure to high temperature extremes environments may also be associated with a decrease in sperm concentration and vitality. The findings of this study suggest that male population should pay attention to avoid exposure to temperature extreme environment, which has important significance for improving the quality of human fertility.