Sperm motility refers to sperm’s ability to move or swim. It’s an essential component in male fertility. Good motility is defined as sperm with forward progressions of at least 25 micrometers per second. Reduced sperm motility has an impact on fertility as sperm needs the ability to move through the female reproductive tract to reach and fertilize the egg. Those with poor sperm motility may be diagnosed with a condition called asthenospermia.
What is sperm motility?
Sperm motility refers to the ability of sperm to move or “swim” efficiently. Sperm motility is critical for fertility, as it affects the ability of the sperm to move through the female reproductive system and reach and penetrate an egg.
Sperm develop motility as they mature while passing through the epididymis, a duct located behind the testis. Motility is related to sperm morphology (size and shape), as defects in sperm structure — such as a missing or malformed tail — may reduce their ability to move effectively.
Sperm motility can be classified as either progressively motile (showing significant forward motion), non-progressively motile (moving randomly or in tight circles), or immotile (not moving). In a normal semen analysis, there should be over 40% total motile sperm and more than 32% progressively motile sperm.
Motility and male fertility
Sperm motility is essential for male fertility and is one of the factors examined in a semen analysis.
Asthenozoospermia, or having a lower-than-normal percentage of motile sperm, may cause infertility. Studies indicate that asthenozoospermia is experienced by anywhere between 19% and 80% of infertile men.
Having 100% immotile sperm is known as complete asthenozoospermia, and occurs in 1 in 5,000 men. With complete asthenozoospermia, it’s difficult to conceive even using assisted reproductive technology such as in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), a fertility procedure that facilitates fertilization by injecting a sperm directly into the egg. Research indicates that completely immotile sperm have lower pregnancy rates after ICSI.
Reduced sperm motility may be caused by or related to:
- smoking
- varicocele (enlarged veins in the scrotum)
- testicular cancer
- older age
- genetic disorders, such as Kartagener’s syndrome
- chromosomal abnormalities
- taking certain medications
Improving sperm motility
While there’s currently no specific treatment for asthenozoospermia, lifestyle changes may improve your sperm health and motility.
Changing your diet may increase your sperm quality. According to a 2019 study, following the Mediterranean diet was linked to increased sperm motility. Other research shows that eating a Western diet high in red meat, sugar, and refined grains was associated with a higher risk of asthenozoospermia, whereas those who ate a plant-based diet had a 54% lower risk.
Certain supplements may also help. A study found that taking selenium and vitamin E supplements for 14 weeks improved semen quality, particularly sperm motility. Another study found increased sperm motility and pregnancy rates in a group of men taking L-carnitine. Remember to consult your doctor before trying any new supplements.
Other healthy lifestyle changes, such as regular exercise and stopping smoking, may also benefit sperm parameters and motility.