Male infertility is any health issue in a man that lowers the chances of his female partner getting pregnant.
About 10% to 15% of couples can't get pregnant with unprotected sex. There are many causes for infertility in men and women. In over a third of infertility cases, the problem is with the man. This is most often due to problems with his sperm production or with sperm delivery.
What Happens Under Normal Conditions?
Your body makes tiny cells called sperm. During sex, ejaculation normally delivers the sperm into the woman's body.
The male reproductive system makes, stores, and transports sperm. Chemicals in your body called hormones control this. Sperm and male sex hormone (testosterone) are made in the two testicles. The testicles are in the scrotum. It is a sac of skin below the penis. When the sperm leave the testicles, they go into a tube behind each testicle. The tube is called the epididymis.
Just before ejaculation, the sperm go from the epididymis into another set of tubes. These tubes are called the vas deferens. Each vas deferens leads from the epididymis to behind your bladder in the pelvis. There each vas deferens joins the ejaculatory duct from the seminal vesicle. When you ejaculate, the sperm mix with fluid from the prostate and seminal vesicles. This forms semen. Semen then travels through the urethra and out of the penis.
Male fertility depends on your body making normal sperm and delivering them. The sperm go into the female partner's vagina. The sperm travel through her cervix into her uterus to her fallopian tubes. There, if a sperm and egg meet, fertilization happens.
The system only works when genes, hormone levels and environmental conditions are right.