Sperm motility is the ability of sperm to move efficiently. This is important in fertility because sperm need to move through the woman’s reproductive tract to reach and fertilize her egg. Poor sperm motility can be a cause of male factor infertility.
In this article, we look at the impact of sperm motility on fertility, as well as the causes of poor sperm motility, and what can be done to improve it.
What is sperm motility?
There are two kinds of sperm motility, referring to the way the individual sperm swim.
Progressive motility refers to sperm that are swimming in a mostly straight line or large circles.
Non-progressive motility refers to sperm that do not travel in straight lines or that swim in very tight circles.
For the sperm to get through the cervical mucus to fertilize a woman’s egg, they need to have progressive motility of at least 25 micrometers a second.
Poor sperm motility or asthenozoospermia is diagnosed when less than 32 percent of the sperm are able to move efficiently.
How does it affect fertility?
Worldwide, around 60 to 80 million couples are affected by infertility, and the rates vary from country to country.
In the United States, the rate is thought to be around 10 percent of couples. The figure is based on the definition of infertility as the inability to conceive after 12 months of trying.
Male factor infertility is when an issue with the man’s biology makes him unable to impregnate a woman. It accounts for between 40 to 50 percent of infertility cases and affects around 7 percent of men.
Male infertility is usually the result of deficiencies in the semen, the most common of which are:
- low sperm count or oligospermia
- poor sperm motility
- abnormal sperm shape or teratospermia