A new study has identified one of the factors behind the decline in male fertility over the past five decades: testis hypoxia, or oxygen deprivation in the testes. Published in Nature Reviews Urology, the study indicates that conditions such as sleep apnoea, high-altitude hiking, and varicocele may adversely affect sperm quality and overall male reproductive health.
Key Findings
Testis hypoxia is described by the study as the lack of oxygen in the testes that could interfere with the production of hormones and genes important for normal sperm. Some chronic conditions such as sleep apnea, varicocele or swelling of the veins in the scrotum, and even hiking at high altitudes could result in chronic deprivation of oxygen.
According to Tessa Lord, a reproductive biologist from The University of Newcastle, Australia, and leader of the study, sleep apnoea and varicocele are significant risk factors. Obstructive sleep apnoea, a disorder that narrows the airway during sleep, reduces the oxygen levels in the blood, which could also affect testicular health. Varicocele is another critical factor that contributes to hypoxia; it is a condition that affects up to 45% of men who experience infertility.
Short-term and long-term effects
In addition, the study investigated the effects of acclimatization at high altitude from activities like hiking that can temporarily lower oxygen supply in the testes. The short-term effects are mostly temporary but may last for a few months if it lasts until one reaches sea level. Long-term hypoxia, caused, for instance, by untreated sleep apnoea and chronic varicocele, is more harmful as it will have prolonged adverse effects on sperm quality.
Implications for Male Fertility
The implications of testis hypoxia are much further-reaching than sperm count alone. Studies indicate that these conditions might lead to disruptions in genes and thus in embryonic development. This disruption can lead to the possibility of causing infertility issues among future offspring.
Although the study highlights the role of testis hypoxia in male fertility decline, it also points out that there is a need for further research to fully understand the downstream effects on offspring health. The authors suggest that fathers suffering from testis hypoxia might pass on developmental issues that could affect their children’s fertility as they grow older.
This research adds a new layer of insight into the complexity of factors leading to male infertility. As much more research is required to fill gaps in knowledge, addressing conditions like sleep apnoea and varicocele may offer important pathways for improving male reproductive health.
