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Pregnant women require more support as stressful events may have impact on future son’s fertility, study suggests

Men are found to have lower total sperm counts and lower concentrations of testosterone if their mothers experienced stressful events during early gestation

Katie O'Malley
Wednesday 29 May 2019 17:23 BST
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Swiss men have some of the worst sperm in Europe, according to new research-

Men whose mothers experience stressful life events in early pregnancy may have reduced sperm counts as adults, a new study finds.

The research found that 63 per cent of men whose mothers were exposed to at least one stressful life event during early gestation had worse sperm quality and lower testosterone concentrations than those who were not exposed, or who were exposure later in pregnancy.

The multi-generational study, published in reproductive medicine journal Human Reproduction, involved 2,804 women in the period between May 1989 and November 1991.

The women completed questionnaires at 18 and 34 weeks’ gestation which included questions about stressful life events during the preceding four months of pregnancy.

Events included the death of a close relative or friend, separation or divorce or marital problems, and problems with children.

Of the 1,454 boys born to the women during this time, 643 of them underwent a testicular ultrasound examination and provided semen and blood samples for analysis when they reached the age of 20.

The findings showed that men who were exposed to stressful life events in early gestation had lower total sperm counts, fewer sperm that could swim well and lower concentrations of testosterone than those exposed to no events.

Meanwhile, men who had been exposed to three or more stressful life events during early gestation had an average of 36 per cent reduction in the number of sperm in their ejaculate.

In addition, the study showed a 12 per cent drop in sperm motility and an 11 per cent decrease in testosterone levels compared to men who were not exposed to any stressful life event during that period.

The senior author of the study and Professor of Reproductive Medicine at the University of Western Australia Roger Hart, said: “This suggests that maternal exposure to stressful life events during early pregnancy, a vulnerable period for the development of male reproductive organs, may have important life-long adverse effects on men’s fertility.

“This contrasts with the absence of any significant effect of exposure to maternal stressful life events in late gestation.”

However, the researchers also took into account several factors that could affect their calculations on low sperm count, such as the mothers’ body mass index, socio-economic status and whether or not the mothers had given birth previously.

Hart acknowledged that while it’s unlikely that exposure to stressful life events in early gestation is the sole cause for a man to be infertile, it could contribute to an increased risk of infertility when added to other factors.

Other lifestyle factors that can impact a man’s fertility include being overweight, central obesity, smoking, excessive alcohol intake, and high blood pressure.

It’s worth noting that one of the limitations of the study is that it was impossible for researchers to measure how stressful life events affect women’s experiences and their perceptions of stress, in addition to their resilience in coping with such pressures.

Prof Hart said: “Our findings suggest that improved support for women, both before and during pregnancy, but particularly during the first trimester, may improve the reproductive health of their male offspring.

“Men should also be made aware that their general health is also related to testicular health, so they should try to be as healthy as possible to ensure that not only do they have the best chance of maintaining fertility, but also of remaining healthy in later life.”

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In light of the findings, several UK medical experts have said that the research does not confirm a cause and effect between stressful situations and male fertility.

“As the authors quite correctly point out there are several potential confounding factors,” says Dr Jane Stewart, chair of the British Fertility Society.

Prof Richard Sharpe, Honorary Professor, MRC Centre for Reproductive Health, University of Edinburgh, adds: "Such studies can never prove cause and effect, but there are biologically plausible explanations, centering around suppression of testosterone production by the fetal testis, that would support the view that too much stress in early pregnancy might be detrimental to optimal male reproductive development."

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