“Infertility in women is often caused by problems with ovulation, the cervix or uterus, or the fallopian tubes. Perhaps the most important risk factor for female infertility is age. Women’s ability to get pregnant declines with age; female fertility declines gradually starting around 35 years of age then declines more dramatically after 40 years of age.   According to the latest WHO statistics, approximately 50–80 million people worldwide sufer from infertility, and male factors are responsible for approximately 20–30% of all infertility cases.  Spermatogenesis is one of the most crucial stages in male fertility.The slightest deviation from the natural course of spermatogenesis can lead to infertility in men.”

National Library of Medicine