Low sperm count means that the fluid (semen) you ejaculate during an orgasm contains fewer sperm than normal. A low sperm count is also called oligospermia (ol-ih-go-SPUR-me-uh). A complete absence of sperm is called azoospermia. Your sperm count is considered lower than normal if you have fewer than 15 million sperm per milliliter of semen.

Having a low sperm count decreases the odds that one of your sperm will fertilize your partner’s egg, resulting in pregnancy. Nonetheless, many men who have a low sperm count are still able to father a child.