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Men whose mothers have suffered stressful events such as divorce or job loss in early pregnancy are more likely to have fewer sperm and less active, researchers said Thursday.
Among 20-year-old Australians born to women who experienced at least three of these events during the first 18 weeks of fetal growth, sperm count was three times lower and mobility decreased by 12% compared to other men in the same group. age, they reported in the newspaper Human Reproduction.
Testosterone levels were also lower, by about ten percent.
"Maternal exposure to stressful life events in early pregnancy, a vulnerable period for developmental organs, can have significant adverse effects on men's fertility," concluded lead author Roger Hart, a professor of Reproductive Medicine at the University of Western Australia.
The link between stress and sperm count disappeared when difficult events – the death of a close relative or friend, marital problems, serious financial problems – only occurred during the last trimester of pregnancy.
Experiments on mice have suggested that early pregnancy – between eight and 14 weeks in humans – is a critical period for the development of male reproduction.
The new findings, the authors note, establish a clear link between stress and sperm health, but not necessarily a cause-and-effect relationship.
Other factors that may accompany stress, such as drug use and smoking, may play equal or greater roles.
But rodent experiments support the theory that stress leads to a reduction in testosterone production in fetal testicles, said Richard Sharpe, an honorary professor at the Center for Reproductive Health of the University of Toronto. 39; Edinburgh not involved in the study.
Read also: Nuts can boost male fertility: study
Always in the "normal" range
"This would support the idea that too much stress in early pregnancy could hinder the optimal development of male reproduction," he wrote in a commentary.
Even the lowest sperm count reported in men whose mothers had previously experienced repeated stress would not in itself cause infertility, although this may be a contributing factor, the researchers said. researchers.
Obesity, alcohol consumption, smoking, high blood pressure, hyperglycemia and possibly exposure to chemicals also affect male fertility.
To mitigate the impact of maternal stress, the Hart team badyzed data from a multigenerational study underway in Western Australia, which recruited some 3,000 women during their 18th week of pregnancy between 1989 and 1991.
Mothers completed questionnaires at weeks 18 and 34, answering questions about stressful life events in previous months.
A total of 1,454 boys born to this cohort were followed by researchers over the next two decades as they grew. At the age of 20, 643 had ultrasound examination of the testes and provided sperm and blood samples for badysis.
It is becoming increasingly clear that the number of sperm in men of European descent has generally decreased over the past 40 years.
A study conducted in 2017 on 43,000 men revealed that sperm concentration had decreased by almost 50% during this period, while remaining within the "normal" range established by the World Health Organization.
At the same time, there has been no significant decline in South America, Asia and Africa.
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