What is it?
Low sperm count means that the fluid (semen) you ejaculate during an orgasm contains fewer sperm than normal. Low sperm count is also called oligospermia. Your sperm count is considered lower than normal if you have fewer than 20 million sperm per milliliter of semen.
A low sperm count decreases the odds that one of your sperm will fertilize your partner's egg, resulting in pregnancy. Nonetheless, many men who have a low sperm count are still able to father a child.
Sperm count may increase if an underlying condition can be identified and treated. Both you and your female partner may need treatment to boost fertility. For some couples, achieving pregnancy requires a procedure such as in vitro fertilization.
The main sign of low sperm count is the inability to conceive a child. Often, there are no other obvious signs or symptoms. In some cases, however, an underlying problem such as an inherited hormonal imbalance or a condition that blocks the passage of sperm may cause signs and symptoms. Low sperm count symptoms may include:
- The inability to conceive a child
- Problems with sexual function — for example, low sex drive or difficulty maintaining an erection (erectile dysfunction)
- Pain, swelling or a lump in the testicle area
- Decreased facial or body hair or other signs of a chromosome or hormone abnormality
Sperm production is complex and requires normal functioning of the testicles (testes) as well as the hypothalamus and pituitary glands — organs in your brain that produce hormones that trigger sperm production. Once sperm are produced in the testicles, delicate tubes transport them until they mix with semen and are ejaculated out of the penis. Problems with any of these systems can affect sperm production. In addition, a number of issues can cause abnormal sperm shape (morphology) or movement (motility). Often the cause of low sperm count isn't ever identified.
Low sperm count can be caused by a number of health issues and medical treatments. Some of these include:
- Varicocele. A varicocele is a swelling of the veins that drain the testicle. This may prevent normal cooling of the testicle, leading to reduced sperm count and fewer moving sperm.
- Infection. Some infections can interfere with sperm production and sperm health or can cause scarring that blocks the passage of sperm. These include some sexually transmitted diseases (STDs), including chlamydia and gonorrhea; inflammation of the prostate (prostatitis); inflamed testicles due to mumps (mumps orchitis); and other infections of the urinary tract or reproductive organs.
- Retrograde ejaculation. This occurs when semen enters the bladder during orgasm instead of emerging out of the tip of the penis. Various health conditions can cause retrograde ejaculation, including diabetes, multiple sclerosis, spinal injuries, and surgery of the bladder, prostate or urethra. Retrograde ejaculation can also be caused by certain medications — particularly medications for enlarged prostate, such as terazosin (Hytrin), tamsulosin (Flomax) and alfuzosin (Uroxatral).
- Lack of ejaculation. Some men with spinal cord injuries or certain diseases can't ejaculate semen, even though they still produce sperm.
- Antibodies that attack sperm. Anti-sperm antibodies are immune system cells that mistakenly identify sperm as harmful invaders and attempt to eliminate them. This is especially common in men who've had a vasectomy.
- Tumors. Cancers and nonmalignant tumors can affect the male reproductive organs directly, or can affect the glands that release hormones related to reproduction (such as the pituitary gland). In some cases, surgery to treat tumors can affect male fertility.
- Undescended testicles. In some males, during fetal development one or both testicles fail to descend from the abdomen into the sac that usually contains the testicles (scrotum).
- Hormone imbalances. Infertility can result from disorders of the testicles themselves or an abnormality affecting the glands in the brain that produce testosterone and other hormones that control the testicles (the hypothalamus or pituitary glands). Low testosterone (male hypogonadism) and other hormonal problems have a number of possible underlying causes.
- Sperm duct defects. The tubes that carry sperm can be damaged by illness or injury. Some men are born with a blockage in the part of the testicle that stores sperm (epididymis) or a blockage of one of the tubes that carry sperm out of the testicles (vas deferens). Men with cystic fibrosis and some other inherited conditions may be born without sperm ducts altogether.
- Chromosome defects. Inherited disorders such as Klinefelter's syndrome — in which a male is born with two X chromosomes and one Y chromosome instead of one X and one Y — cause abnormal development of the male reproductive organs.
- Problems with sexual intercourse. These can include trouble keeping or maintaining an erection sufficient for sex (erectile dysfunction), premature ejaculation, painful intercourse, or psychological or relationship problems that interfere with sex.
- Celiac disease. A digestive disorder caused by sensitivity to gluten, celiac disease can cause male infertility. Fertility may improve after adopting a gluten-free diet.
- Certain medications. Testosterone replacement therapy, long-term anabolic steroid use, cancer medications (chemotherapy), certain antibiotics, some ulcer medications and certain other medications can impair sperm production and decrease male fertility.
Overexposure to certain environmental elements such as heat, toxins and chemicals can reduce sperm production or sperm function. Specific causes include:
- Pesticides. Some men exposed to pesticides such as ethylene dibromide and organophosphates have lowered sperm counts. Pesticide exposure has also been linked to testicular cancer. Most studies have been done on men who work in agriculture or live in agricultural areas.
- Heavy metal exposure. Exposure to lead or other heavy metals also may cause infertility.
- Exposure to radiation or X-rays. Exposure to radiation can reduce sperm production. It can take several years for sperm production to return to normal. With high doses of radiation, sperm production can be permanently reduced.
- Overheating the testicles. Frequent use of saunas or hot tubs may temporarily lower your sperm count. Sitting for long periods or wearing tight clothing also may increase the temperature in your scrotum and reduce sperm production.
- Prolonged bicycling. Prolonged bicycling is another possible cause of reduced fertility due to overheating the testicles. In some cases, bicycle seat pressure on the area behind the testicles (perineum) can cause numbness in the penis and erectile dysfunction.
Health, lifestyle and other causes
Some other causes of low sperm count include:
- Illegal drug use. Anabolic steroids taken to stimulate muscle strength and growth can cause the testicles to shrink and sperm production to decrease. Use of cocaine or marijuana may temporarily reduce the number and quality of your sperm as well.
- Alcohol abuse. Heavy drinking can lower testosterone levels, cause erectile dysfunction and decrease sperm production. Liver disease caused by excessive drinking may also cause fertility problems.
- Tobacco smoking. Men who smoke may have a lower sperm count than do those who don't smoke. Secondhand smoke also may affect male fertility.
- Emotional stress. Stress may interfere with certain hormones needed to produce sperm. Your sperm count may be affected if you experience severe or prolonged emotional stress. A problem with fertility itself can sometimes become long term and discouraging, producing stress.
- Vitamin deficiency. Deficiencies in nutrients such as vitamin C, selenium, zinc and folate may contribute to decreased sperm production and male infertility.
- Weight. Obesity can cause hormone changes that reduce male fertility. Men who are underweight also may have reduced fertility.
- Age. Men older than 35 begin to have a gradual decline in sperm production.
- Incomplete sperm collection. Lower than normal sperm counts can result from testing a sperm sample that was taken too soon after your last ejaculation; was taken too soon after an illness or stressful event; or didn't contain all of the semen you ejaculated because some was spilled during collection. For this reason, results are generally based on several samples taken over a period of time.
A number of risk factors are linked to low sperm count and other problems that can cause low sperm count. They include:
- Being age 35 or older
- Smoking tobacco
- Abusing alcohol
- Using certain illegal drugs
- Being overweight
- Being underweight
- Having certain past or present infections
- Being exposed to toxins
- Overheating the testicles
- Having a prior vasectomy or vasectomy reversal
- Being born with a fertility disorder or having a blood relative with a fertility disorder
- Having certain medical conditions, including tumors and chronic illnesses
- Undergoing medical treatments, such as surgery or radiation for cancer
- Taking certain medications
- Bicycling for long periods, especially on a hard seat or poorly adjusted bicycle
Infertility caused by low sperm count can be stressful for both you and your partner. Complications can include:
- Surgery or other treatments for an underlying cause of low sperm count or other reproductive problems
- Expensive and involved reproductive techniques such as in vitro fertilization
- Stress related to the inability to have a child
When you see a doctor because you're having trouble getting your partner pregnant, he or she will try to determine the underlying cause. Even if your doctor thinks low sperm count is the problem, you and your partner may both need tests to rule out other causes of infertility and to look for any underlying health problems. Testing and diagnosis may involve the following.
General physical examination and medical history
This includes examination of your genitals and questions about any inherited conditions, chronic health problems, illnesses, injuries or surgeries that could affect fertility. Your doctor may also ask about your sexual habits and questions about your sexual development.
A low sperm count is diagnosed as part of a semen analysis test. Sperm count is generally determined by examining semen under a microscope to see how many sperm appear within squares on a grid pattern. In some cases, a computer may be used to measure sperm count.
To collect a semen sample, your doctor will have you masturbate and ejaculate into a special container. It's also possible to collect sperm for examination during intercourse, using a special condom. Often sperm counts fluctuate from one specimen to the next. In most cases, several semen analysis tests are done over a period of time to ensure accurate results.
One of the most common causes of low sperm count is an incomplete or improper collection of a sperm sample. Most doctors will check two or more semen samples over time to ensure consistency between samples. To ensure accuracy in a collection, your doctor will want to:
- Ensure all of your semen makes it into the collection cup or collection condom when you ejaculate
- Wait at least three months after you've recovered from an illness or stressful event to collect a sperm sample
- Have you abstain from ejaculating for at least 48 hours before collecting a sample (but not for more than seven days)
Semen analysis results
Normal sperm densities range from 20 million to greater than 100 million sperm per milliliter of semen. You are considered to have a low sperm count if you have fewer than 20 million sperm per milliliter. Some men have no sperm in their semen at all. This is known as azoospermia (ay-zoh-uh-SPUR-me-uh).
Your chance of getting your partner pregnant decreases along with decreasing sperm counts:
- Fewer than half the men with sperm counts between 12.5 million and 25 million sperm per milliliter are able to get their partner pregnant.
- Fewer than one-quarter of men with sperm counts less than 12.5 million sperm per milliliter are able to get their partner pregnant.
There are many factors involved in reproduction, and some men with low sperm counts have fathered children. Likewise, some men with normal sperm counts have been unable to father children. The number of sperm in your semen is only one factor. Even if you have enough sperm, you're much more likely to get your partner pregnant if at least half of your sperm have a normal shape (morphology) and show normal forward movement (motility).
Depending on initial findings, your doctor may recommend additional, more specialized tests to look for the cause of your low sperm count and other possible causes of male infertility. These can include:
- Scrotal ultrasound. This test uses high-frequency sound waves to produce images inside your body. A scrotal ultrasound can help your doctor look for evidence of a varicocele or obstruction of the part of the testicle that stores sperm (epididymis). A small wand is moved over the surface of your testicle sac to produce images on a video screen.
- Transrectal ultrasound. This is similar to a scrotal ultrasound — but for this test, a small lubricated wand is inserted into your rectum. It allows your doctor to check your prostate, and check for blockages of the tubes that carry semen (ejaculatory ducts and seminal vesicles).
- Hormone testing. Hormones produced by the pituitary and hypothalamus glands and the testicles play a key role in sexual development and sperm production. Your doctor may recommend a blood test to determine the level of testosterone and other male hormones that affect sperm count.
- Post-ejaculation urinalysis. This test involves collecting a urine sample after orgasm. The urine is checked for the presence of sperm. Sperm in your urine can indicate your sperm are traveling backward into the bladder instead of out your penis during ejaculation (retrograde ejaculation).
- Genetic tests. These tests are used if your doctor suspects your reduced sperm count or other fertility problems could be caused by an inherited sex chromosome abnormality. When sperm concentration is extremely low, genetic causes could be involved. A blood test can reveal whether there are subtle changes in the Y chromosome — signs of a genetic abnormality. Genetic testing may also be ordered to diagnose Klinefelter's syndrome or cystic fibrosis.
- Testicular biopsy. This test involves removing samples from the testicle with a needle. It may be used if your semen analysis shows no sperm at all. The results of the testicular biopsy will tell if sperm production is normal. If it is, your problem is likely caused by a blockage or another problem with sperm transport.
- Anti-sperm antibody tests. These tests are used to check for immune cells (antibodies) that attack sperm and can affect their ability to function. You are especially likely to have anti-sperm antibodies if you've had vasectomy reversal.
- Vasography. In some cases, contrast dye is injected into each of the tubes that carry sperm (vas deferens) to check for blockage.
- Specialized sperm function tests. A number of different tests can be used to evaluate how well your sperm survive after ejaculation, how well they can penetrate an egg, and whether there's any problem attaching to the egg. If you do have a low sperm count, having healthy sperm can be an important factor in male fertility.