It takes only one sperm to fertilize an egg and start a pregnancy. However, to overcome the daunting odds of a sperm successfully navigating the female reproductive tract to penetrate the egg, a man must contribute tens of millions of sperm to the effort. Of all of those sperm, only about 200 reach the egg, while all of the others give out or get lost along the journey.
Sperm Number
The semen of a normal, healthy male contains between 20 million to 100 million sperm per milliliter. Doctors diagnose a man with a low sperm count -- a condition called oligospermia -- if his semen contains less than 20 million sperm per milliliter. Although it could happen, a man with oligospermia is unlikely to get a woman pregnant naturally. The condition called azoospermia means that there are no sperm in the semen at all.
Statistics
According to the Mayo Clinic, less than half of men with a sperm count between 12.5 million to 25 million can get their partners pregnant. Less than 25 percent of men with sperm counts lower than 12.5 million per milliliter can get their partners pregnant.
Sperm Function
The number of sperm present in a semen sample is just one index of male fertility. Doctors also evaluate the sperms' morphology, or overall shape, and motility, or ability to swim properly. As a rough estimate, about 1/2 the sperm in a sample must have normal morphology and motility for a man to have a normal ability to father children. A man with a lower sperm count but good morphology and motility might have an equal shot at fertility as a man with a much higher sperm count but poor morphology and motility.
Boosting Sperm Count
Some herbs and natural preparations might increase sperm count, but the evidence is not definitive. Possible sperm-count boosters include ginseng, vitamins B12, C and E, zinc and selenium. Men should not use these supplements without consulting a doctor because they can interfere with other medications, and large doses can be toxic.
Assisted Reproduction
A man with a low sperm count can still father children using assisted reproduction technology, or ART. Using in vitro fertilization, or IVF, doctors can incubate an egg in a laboratory dish with a small number of sperm to overcome the odds and allow men with few sperm to father children. Even men with next to no sperm can father children through an IVF technique called intracytoplasmic sperm injection, or ICSI. In ICSI, the doctor injects a single sperm directly into an egg to ensure fertilization.
