Sperm motility is the ability of sperm to move efficiently. This is important in fertility as sperm move through the female reproductive tract to reach and fertilize the egg. Low 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.
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?
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
Around 90 percent of male infertility issues are caused by low sperm count, but poor sperm motility is an important factor also.
The causes of low sperm motility vary, and many cases are unexplained.
Damage to the testicles, which make and store sperm, can impact on the quality of sperm.
Common causes of testicle damage include:
The long-term use of anabolic steroids can reduce sperm count and motility. Drugs, such as cannabis and cocaine, as well as some herbal remedies, can also affect semen quality.
Varicocele, a condition of enlarged veins in the scrotum, has also been associated with low sperm motility.
Semen analysis is the most basic and useful test, and it can detect 9 out of 10 men with a fertility problem. The test assesses the formation of the sperm, as well as how they interact in the seminal fluid.
The sample is usually collected by masturbation. The man will be asked to abstain from sex for between 2 and 7 days before collecting the sample to increase the volume of semen.
It is necessary for the whole ejaculation is be collected in a sterile container to ensure the test results are complete.
The sample is usually collected in a private room at the doctor’s office or collection facility, though in some circumstances it can be produced at home. If this is the case, the sample will need to be delivered for analysis within an hour.
The sample should not be stored in the fridge, and doctors recommend holding it close to the body during transportation to keep it at body temperature. This will ensure it is the best possible quality when it is analyzed.
Sometimes, the sample can be collected via sexual intercourse, either in a specially designed condom or by withdrawing before ejaculation. It is important not to use a commercial condom for this, as many have lubricants or spermicides that can taint the sample.
Samples can vary for different reasons, including the length of abstinence from sexual intercourse and illness. As a result, two samples are usually collected. They may be anywhere from 2 to 4 weeks apart.
If the percentage of progressively motile sperm is less than 32 percent, the diagnosis may be poor sperm motility.
There are lifestyle choices people can make that will help improve the quality of their sperm. Smoking can reduce fertility and has been shown to affect sperm motility.
Recreational drugs, including cannabis, amphetamines, and opiates, and excessive alcohol consumption also reduce sperm quality. Doctors advise people to avoid these if they are trying to conceive.
Being overweight with a body mass index of 25 or more can affect both the quality and quantity of sperm.
There is a link between an increased temperature of the scrotum and a reduction in the quality of sperm. The ideal, sperm-producing temperature is around 94 °F, or just below body temperature, so loose-fitting underwear and taking simple measures to keep the testicles cool may help.
Helpful steps include taking regular breaks if working in a hot environment, and getting up and moving around if a person spends long periods sitting down.
There is no evidence that complementary therapies are effective in improving sperm motility.
Poor sperm motility can lead to male infertility, but treatments are available. Some options include:
- Intrauterine insemination (IUI): Also known as artificial insemination, the IUI procedure involves sperm being collected and washed. The fastest moving sperm are then inserted into the womb using a fine plastic tube.
- In vitro fertilization (IVF): During IVF, the woman is given medication to encourage the production of eggs, which are removed from the ovaries and fertilized with sperm in the laboratory. The resulting embryo is then returned to the womb to develop.
- Sperm donation: A person wanting to conceive may be able to receive a sperm donation from a donor for use in an IVF procedure.
Anyone who has been trying unsuccessfully to conceive for more than 12 months is advised to speak to their doctor to check for any fertility issues there may be.