The Role of Sperm Motility

Sperm motility refers to the sperm’s ability to move and swim. Motility is one of several parameters considered in a sperm analysis. Sperm motility is a very important aspect of fertility because sperm need to travel through the reproductive tract to fertilize an egg. Poor sperm motility is a common cause of male infertility.

What Is Normal Sperm Motility?
Normal sperm motility means that at least 40% of the sperm in the sample are moving by the WHO 5th edition criteria. Progressive motility is also taken into consideration when evaluating a sperm sample. This refers to how many sperm are actually moving from one place to another with progressive motion instead of twitching or moving in circles. A normal progressive motility rate is 32% of the sperm. Finally, a fertility specialist will consider how many sperm in the sample swim in a rapid, straight line as they are most likely to fertilize an egg compared to slow-moving sperm that don’t travel straight. At least 12% of sperm should move quickly in a straight line.

What Causes Low Motility?
While many cases of poor sperm motility are unknown, there are many factors that can cause motility problems. Damage to the testicles is a common cause of motility issues as it affects sperm quality. Undescended testicles, testicular surgery, testicular cancer, surgery, and congenital problems may also reduce sperm motility. Some drugs, including cocaine and anabolic steroids, can also impact sperm quality. It’s also possible for poor habits like smoking to negatively affect motility.

Sperm Motility and Male Infertility
Male infertility is often the result of one or more sperm deficiencies. Most cases of infertility are caused by low sperm count, abnormal sperm shape, or poor motility. While most cases of male infertility are attributed to low sperm count, sperm motility is still an important factor that shouldn’t be overlooked. Even with sufficient sperm count, it can be difficult to conceive if the sperm aren’t able to travel quickly or efficiently.

Treating Low Sperm Motility
A common condition called varicocele, or enlargement of the veins inside the scrotum can also affect sperm motility. It’s estimated that this condition affects about 15% of all adult men and about 40% of men who visit a fertility clinic. This condition can be treated with microsurgical repair to reduce the risk of a recurrence and improve not only sperm motility but also sperm count and morphology. Fertility specialist Dr. Parviz Kavoussi performs surgical repair of varicoceles with a small 1-inch incision. As Dr. Kavoussi states, “Microsurgical repair is a superior treatment for varicoceles in subfertile men”, based on American Society for Reproductive Medicine statements.

There are also lifestyle changes that can support healthier sperm production. This includes maintaining a healthy weight, regular exercise, a healthy diet, and quitting alcohol and smoking.