A new study, published in the journal Human Reproduction, found that men whose mothers experience stressful events early in pregnancy are more likely to have reduced sperm counts and lower testosterone levels when they become adults.
The study, by researchers at the University of Western Australia, surveyed 2,804 women during different stages in their pregnancies between May 1989 and November 1991. Their sons were then asked to undergo testicular ultrasounds and provide semen and blood samples for analyses when they reached the age of 20. Of the 1,454 boys who were born to the pregnant women initially surveyed, 643 of them agreed to participate.
Researchers found that 63 percent of men whose mothers had reported at least one stressful life event during the early stages of pregnancy had lower testosterone levels and lower sperm counts than men whose mothers did not experience a stressful life event early in pregnancy. The study took into account other factors that could affect men’s sperm counts and testosterone levels, including weight, alcohol consumption, and smoking history.
The study also found that men whose mother reported three or more stressful life events in early pregnancy had an average of 36 percent lower sperm counts compared to men whose mothers experienced less stress in pregnancy. Of note, stressful life events after 34 weeks gestation did not seem to impact the sons’ sperm counts and testosterone levels.
“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,” said Roger Hart, lead author of the study and Professor of Reproductive Medicine at the University of Western Australia.
“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,” said Hart.