Past research has associated stress with a number of health problems, including heart disease, asthma, obesity and depression. Now, a new study suggests stress can reduce sperm and semen quality, which could have implications for male fertility.
According to the American Society for Reproductive Medicine, in around 40% of infertile couples the male partner is the sole cause or contributing cause of infertility.
The main cause of male infertility is sperm abnormalities, including low sperm production or misshapen or immobile sperm. Medical conditions - such as undescended testicles or ejaculation problems - can lead to sperm abnormalities, as well as health and lifestyle factors.
In this latest study - published in the journal Fertility and Sterility and led by researchers from Columbia University's Mailman School of Public Health in New York, NY, and Rutgers School of Public Health in Piscataway, NJ - the team investigated whether stress may affect sperm and semen quality.
Life stress 'led to lower semen quality'
To reach their findings, the researchers assessed 193 men aged 38 to 49 between 2005 and 2008. All men were a part of the Study of the Environment and Reproduction at the Kaiser Foundation Health Plan in Oakland, CA.
Men who experienced two or more stressful life events in the past year had lower sperm quality than men who did not experience any stressful life events, according to researchers.
As part of the study, the men were required to complete a series of tests that measured levels of stress, including that from the workplace, stressful life events and overall perceived stress.
They were also required to provide semen samples. Using standard fertility testing methods, researchers from the University of California, Davis, analyzed semen concentration, and sperm shape (morphology) and movement (motility) in each sample.
The researchers found that men who experienced two or more stressful life events in the past year had a lower percentage of sperm motility and a lower percentage of sperm of normal morphology, compared with men who did not experience any stressful life events. They note this finding remained even after accounting for other factors that may influence semen quality, such as age, other health problems and history of reproductive health problems.
Although workplace stress did not directly affect semen quality in the men, the researchers found that those who experienced job strains had lower levels of the hormone testosterone in their semen, which could affect reproductive health.
In addition, they found that regardless of the levels of stress experienced, men who were unemployed had lower semen quality than those who were employed.
How can stress affect semen quality?
Although the researchers are unable to pinpoint exactly how stress affects the quality of semen, they do present some theories.
They say stress could activate the release of glucocorticoids - steroid hormones that affect the metabolism of carbohydrates, fats and proteins - which could reduce testosterone levels and sperm production.
Furthermore, they say stress could trigger oxidative stress - physiological stress on the body caused by damage from unneutralized free radicals - which has been associated with semen quality and fertility.
Commenting on the findings, first study author Teresa Janevic, PhD, an assistant professor at Rutgers School of Public Health, says:
"Stress has long been identified as having an influence on health. Our research suggests that men's reproductive health may also be affected by their social environment."
The researchers note that this is the first study to use subjective and objective measures of stress and, as a result, find links with reduced semen quality.
In a recent spotlight feature, Medical News Today looked at whether infertility is primarily seen as woman's problem, and whether there needs to be more awareness surrounding male infertility.