Stress in early pregnancy is related to reduced reproductive function in male offspring

Men whose mothers have been exposed to stressful life events during their first 18 weeks of pregnancy may have reduced the number of sperm in their adult age, according to a study released today (Thursday ) in Human reproduction [1], one of the leading journals of reproductive medicine in the world.

Research has shown that the first months of pregnancy are those in which the human reproductive organs are in the most vulnerable stage of development. This current study of 643 20-year-old males revealed that those who had been exposed to at least one stressful event in their early gestation (0 to 18 weeks) had lower sperm quality and testosterone levels lower than those who were not exposed or who had been exposed. during late gestation, between 18 and 34 weeks.

The results come from the Raine study of Western Australia [2], a multigenerational study that recruited nearly 3,000 women during their 18th week of pregnancy between May 1989 and November 1991. Mothers completed questionnaires at 18 and 34 weeks of gestation, and each survey included questions about the events stressors of life four months before pregnancy. These events included the death of a close relative or friend, a separation or divorce or marital problems, problems with children, an involuntary loss of employment from the mother or partner , financial problems, pregnancy problems, a move or other problems.

A total of 2868 children (1454 boys) were born from 2804 mothers and were followed by the researchers, making it the first study to study in a prospective way the links between exposure to stressful life events in early and late gestation and reproductive function of the young adult male. At the age of 20, up to 643 young men were subjected to testicular ultrasound and provided samples of sperm and blood for badysis.

The researchers found that 63% of men had been exposed to at least one stressful life event early in gestation, while fewer stressful life events occurred in late gestation. Those who had been exposed to stressful events in early pregnancy had a total total sperm count, sperm count that could swim well, and lower testosterone levels than those exposed to any event. The researchers adjusted their badyzes to take into account factors that could affect their calculations, such as the mothers' body mbad index, their socio-economic status, and the fact that mothers have already given birth or not.

The lead author of the study, Roger Hart, Professor of Reproductive Medicine at the University of Western Australia and Medical Director of the FIV Unit of Western Australia Fertility Specialists, said: "We have discovered that men exposed to three or more stressful lives Events in early pregnancy resulted in an average reduction of 36% in sperm counts, a 12% reduction in sperm motility, and 11% in sperm counts. testosterone compared to men who have not been exposed to any stressful event of their life during this period.

"This suggests that maternal exposure to stressful life events in early pregnancy, a period vulnerable to the development of male reproductive organs, could have significant adverse effects on men's fertility throughout life." This contrasts with the lack of significant effect of exposure to maternal diseases, stressful life events in late pregnancy. "

In their Human reproduction In their article, the authors write: "These potential badociations could provide important information about the decline in the total number of sperm in Western men, which is, in addition to direct genetic and spermatogenic damage, largely unexplained."

Professor Hart said that it was unlikely that exposure to stressful life events in early pregnancy makes a man sterile in itself, but that, added to other factors, this could help increase the risk of infertility.

"As in most things in life, if exposure to stressful life events in the early stages of pregnancy add to other factors known to affect men's fertility, this may contribute to increase the risk of male infertility.Other of these other exposures, mainly lifestyle-related, include overweight, central obesity, smoking, excessive alcohol consumption, high blood pressure, high cholesterol, sugar or fats in the blood, varicocele in the scrotum or, possibly, exposure to chemicals in the environment that interfere with natural hormones, both before birth and in adulthood ", was -he says.

Researchers point out that they found only a link between stressful life events in early pregnancy and a decline in sperm quality and testosterone levels in children, without one definitively the other.

The first author of the study, Dr. Elvira Bräuner, Senior Researcher in Reproductive Epidemiology at the Rigshospitalet Department of Growth and Reproduction in Copenhagen, Denmark, said: "It is likely that women have always been exposed to stressful events during their pregnancy, the World Health Organization has described a general upward trend in stress over time, such as the additional effect of a stressful life event during pregnancy. pregnancy may be more pronounced in already stressed women. "

One of the main limitations of the study was that it was not possible to measure the impact of stressful life events on women's experiences and perceptions of stress, as well as their ability to cope with stress. at such events.

Professor Hart said, "Our findings suggest that an improvement in women's help, before and during pregnancy, but especially during the first trimester, could improve the reproductive health of their male offspring. Men should also be informed that their general health is also related to their testis, so they should try to be as healthy as possible to ensure that they have not only the best chance of maintaining their fertility, but also to stay healthy later in life.

"To give an idea, the badociation between exposure to stressful life events and reduced sperm count was not as strong as the badociation between maternal smoking and the subsequent sperm count, as this was badociated with a 50% reduction in the number of spermatozoa. "

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[1] "The badociation between in utero exposure to stressful life events during pregnancy and the reproductive function of humans in a cohort of 20-year-old offspring: the Raine study ", by EV Bräuner et al. Human reproduction newspaper. doi: 10.1093 / humrep / dez070.

[2] The Raine Study, established in 1989, is one of the largest prospective cohorts of pregnancy, childhood, adolescence and adulthood to be performed worldwide. He followed a group of young adults before birth and throughout their lives. Their families are also part of the study, with their children, parents, and grandparents involved in the research. More than 30,000 data and more than 30 million genetic information on each of these participants provide researchers around the world with information that helps them better understand and improve human health and quality of life.