Stress has a huge impact on our reproductive health. Long-term stress can also have a negative impact on our sexual health. However, the latest study shows that sperm motility is better after a stressful event, not during one.

A new study from the University of Colorado Anschutz Medical Campus sheds light on how stress affects reproduction and may help improve fetal development outcomes.

Sperm quality and fertility have declined over the past 50 years, possibly due to increased environmental stress. But researchers still don’t fully understand how these changes affect sperm.

The study, published in Nature Communications, shows that stress affects sperm motility, or their ability to move through the female reproductive system to fertilize an egg.

After the stress was over, changes were observed in small particles called extracellular vesicles (EVs), which help in sperm development.

The researchers found that these changes occurred not during the experience of stress, but after the cause of the stress had passed.

“Our research shows that sperm motility significantly improves after stress, which could help increase birth rates after stressful times like the COVID-19 pandemic,” said Tracy Bell, lead author of the study.

This effect has been observed in both human and animal studies, suggesting a widespread relationship across different species.

Dr. Nicole Moon, first author of the study, compared the process to a car running more efficiently with a little extra fuel.

He explained that stress-induced adjustments help sperm improve energy production and movement.

Dr. Moon said, “Imagine you have a car struggling to climb a steep hill. When the engine is stressed, the car becomes less efficient. However, by applying a little more gas, you can increase overall performance for a smoother drive. Just as your car becomes more efficient under stress, with the right adjustments, cells improve their energy production and speed in the presence of stress-inducing factors.”

Although the study focused on men, researchers are also exploring how stress affects both partners’ and fetuses’ development, particularly the brain.

Co-author Dr. Neil Epperson emphasized that understanding how stress affects fertility and is passed down through generations is crucial to improving reproductive health.

The research team is continuing studies to determine how stress affects sperm and fertilization, and plans further testing to deepen understanding of these mechanisms.