What Does Low Sperm Motility Really Mean?
Your semen analysis says asthenozoospermia, and now you are worried. Here is what low motility actually measures, how much it affects your chance of conceiving, and the evidence-based steps that can help sperm swim better.
Few lines on a semen analysis cause as much worry as a low motility result. If your report reads asthenozoospermia, it simply means a lower than expected share of your sperm are moving well. It is one of the most common findings on a male fertility test, and importantly, one of the most responsive to change.
Motility matters because sperm have a journey to make. To fertilise an egg, they must swim from the vagina, through the cervix, and up the fallopian tube. Sperm that cannot move forward effectively rarely complete that trip, no matter how many of them there are.
Key takeaways
- Motility is how well sperm move; it is measured as total motility and progressive motility.
- The WHO 2021 lower reference limit is 42% total and 30% progressive motility.
- A single low result is not a diagnosis. Motility varies between samples and needs confirming.
- Because sperm take about 74 days to mature, improvements show up after two to three months.
What sperm motility measures
Sperm motility describes the percentage of sperm in a sample that are moving, and how well they move. A laboratory grades a fresh sample under a microscope and reports two figures you will see on almost every analysis.
- Total motility is the share of all sperm showing any movement at all, whether swimming forward or simply twitching in place.
- Progressive motility is the share swimming actively forward in a mostly straight line, which is the movement that actually reaches an egg.
Progressive motility is the more meaningful of the two for natural conception. A sample can have reasonable total motility while too few sperm are genuinely progressing, so it is worth reading both numbers together rather than either one alone.
What counts as low motility
The World Health Organization sets reference limits based on a large study of men who fathered a child within twelve months. Your laboratory compares your result against these thresholds.
| Measure | WHO 2021 lower limit | Below this is called |
|---|---|---|
| Total motility | 42% | Asthenozoospermia |
| Progressive motility | 30% | Asthenozoospermia |
Sitting just below a limit is not the same as being infertile. Reference limits describe the lowest 5% of fertile men, which means plenty of men below the line still conceive naturally. The number is a prompt to look closer, not a verdict.
A low motility result is the start of a conversation, not the end of one.
Why motility drops
Sperm movement is fragile and sensitive to the body's environment. Several everyday and medical factors can lower it, and many of them are within your control.
- Heat. The testes work best a few degrees below core body temperature. Frequent hot baths, saunas, tight underwear and long hours with a laptop on the lap all raise scrotal temperature.
- Varicocele. Enlarged veins in the scrotum are one of the most common and treatable causes of poor motility in men.
- Oxidative stress. Smoking, heavy alcohol use and poor diet flood sperm with unstable molecules that damage the tail and slow movement.
- Infection. Untreated genital tract infections can impair motility and sometimes clump sperm together.
- Long abstinence. Very long gaps between ejaculation increase the share of older, less mobile sperm in a sample.
How to improve sperm motility
Motility is one of the most responsive parameters to lifestyle change, which is genuinely good news. The evidence points most strongly to a handful of changes, and they work best when given a full sperm cycle to take effect.
- Keep the area cool. Swap very hot baths for warm, choose looser underwear, and keep laptops off your lap.
- Stop smoking and moderate alcohol. Both are strongly linked to lower motility, and the effect is reversible over time.
- Eat for your sperm. Diets rich in antioxidants, zinc, selenium and folate support healthier movement. Read our guide to nutrition for sperm health.
- Move your body. Regular moderate exercise improves motility, while a sedentary routine and excess weight work against it.
- Get a varicocele checked. If a physical cause is present, treating it can produce some of the largest gains.
Before you change anything, it helps to understand where you stand. Our semen parameter check compares each of your values against the WHO 2021 reference ranges, so you can see which parameters are within range and which to raise.
When to see a doctor
Speak with a doctor or fertility specialist if a low motility result is confirmed on a repeat test, if you have been trying to conceive for twelve months without success, or six months if your partner is over 35. A specialist can check for a varicocele, infection or hormonal cause, and discuss options if lifestyle change alone is not enough.
This article is educational, not a diagnosis. Sperm parameters vary between samples, and only a qualified clinician can interpret your results in the context of your health. Always confirm findings and next steps with a doctor.
Sources
- World Health Organization. WHO laboratory manual for the examination and processing of human semen, 6th edition. 2021.
- Agarwal A, et al. Male infertility. The Lancet. 2021.
- Practice Committee of the American Society for Reproductive Medicine. Diagnostic evaluation of the infertile male. 2015.