Common Causes Male Overview For a man to be fertile, his sperm cells must be healthy and be transported to their destination – the egg. Most cases of male infertility are due to sperm abnormalities, yet any of the following can play a role:
Sperm basics Fertilization depends on sperm that are properly shaped (morphology) and able to move (motility) rapidly and accurately toward the egg. Impaired motility and morphology can result in sperm not reaching the egg. Sperm count or concentration refers to the number of sperm cells per milliliter of semen. Men with 10 million or fewer sperm per milliliter are considered subfertile. Approximately 20 million or higher is considered average; 40 million sperm or higher per milliliter indicates increased fertility. |
Advanced Paternal Age
|
It has become common knowledge that women's fertility declines with age. It's also been assumed that men have no similar "biological clock." Scientists are learning more about how that assumption is incorrect.