Fertility trying to conceive

What Causes Low Sperm Count?

Hillary Bennetts

What Causes Low Sperm Count?

Table of contents

  • What Causes Low Sperm Count?
  • What Does Low Sperm Count Mean?
  • How Common is Oligospermia?
  • Risk Factors
  • Causes of Low Sperm Count
  • How Is Low Sperm Count Diagnosed?
  • How is Oligospermia Treated?
  • How to Help Prevent Low Sperm Count

0 min read

What Causes Low Sperm Count?

Sperm meeting egg sounds like a simple concept, but there are so many factors that go into this process to achieve a pregnancy. 

The quality of sperm (and the quality of eggs) are crucial to fertility outcomes. One component of sperm quality is sperm count. That is, the number of sperm that are contained in a man’s ejaculate.

It only takes one sperm to fertilize an egg, but the journey of a sperm getting to an egg isn’t easy. So the more sperm you have, the better your chances of achieving a pregnancy.

Let’s take a closer look at some of the causes of low sperm count, how you can find out if you have low sperm count, and how you can support sperm count.

What does low sperm count mean?

Low sperm count, also called oligospermia (ol-ih-go-SPUR-me-uh), means that the fluid (semen) you ejaculate during an orgasm contains fewer sperm than normal. Specifically, you are considered to have a low sperm count if you have fewer than 15 million sperm per milliliter or less than 39 million sperm total per ejaculate. 

Having a low sperm count decreases the odds that one of your sperm will fertilize your partner's egg, resulting in pregnancy. 

How common is oligospermia?

We don’t have reliable data on how many people have oligospermia. The condition isn't usually diagnosed unless a couple seeks testing because they have been unable to conceive. 

There are an estimated 180 million couples throughout the world who are dealing with infertility, but there are many other causes, and some unexplained causes, of infertility.

Risk factors

It isn’t always possible to control sperm count, but there are a number of risk factors that are linked to low sperm count. Many of these are modifiable lifestyle factors. This means that a person can make changes on their own to decrease the risk of low sperm count. Some modifiable risk factors include the following:

  • Smoking tobacco
  • Drinking alcohol
  • Using certain illicit drugs
  • Being overweight
  • Being severely depressed or stressed
  • Certain past or present infections
  • Toxin exposure
  • Overheating the testicles

Causes of Low Sperm Count

Similar to risk factors, there are many potential causes of low sperm count. They can be related to traits that you're born with or lifestyle choices that you’ve made. We know that things like smoking, drinking alcohol, and taking certain drugs can lower sperm numbers. But the following causes of low sperm count are typically unrelated to lifestyle factors. 


Varicoceles are swollen veins in the scrotum. They harm sperm growth by blocking proper blood drainage. Varicoceles are more common in infertile men. 

Retrograde Ejaculation

Retrograde ejaculation is when semen goes backwards in the body, into your bladder instead of out the penis. This happens when nerves and muscles in your bladder don't close during orgasm. Semen may have normal sperm, but the semen does not come out of the penis, so it cannot reach the vagina.

Retrograde ejaculation can be caused by surgery, drugs or health problems of the nervous system. Signs are cloudy urine after ejaculation and less fluid or "dry" ejaculation.

Trauma to the Testicles

Trauma to the testicle or scrotum can affect the way they function, impacting sperm production. 

Genetic Fertility Disorders

Being born with a fertility disorder or having a blood relative, such as a brother or father, with a fertility disorder, can impact sperm production. Being aware of a family history of fertility disorders is helpful in your own fertility journey, but testing is available if not.


Sometimes the tubes through which sperm travel can be blocked. Repeated infections, surgery, swelling, or developmental defects can cause blockage. Any part of the male reproductive tract can be blocked, which prevents sperm from the testicles from leaving the body during ejaculation.


Hormones made by the pituitary gland tell the testicles to make sperm. Disrupted hormone production can impact sperm production. Hormone disruption can be caused by certain lifestyle factors, but can also be related to other underlying issues. 


Certain drugs can change sperm production, function, and delivery. These drugs are most often given to treat conditions including the following:

  • Arthritis
  • Depression
  • Digestive problems
  • Anxiety or depression
  • Infections
  • High blood pressure
  • Cancer

Immunologic Infertility

In rare cases, a man's body makes antibodies that attack his own sperm. Antibodies are most often made because of injury, surgery, or infection. They keep sperm from moving and working normally. 

How Is Low Sperm Count Diagnosed?

A person or couple may seek the support of a healthcare professional if they are having trouble getting pregnant. Checking sperm count is one of several potential underlying causes. Here’s how it’s done:

General physical examination and medical history

A physical exam involves an evaluation of the male genitals as well as a review of questions about any inherited conditions, chronic health problems, sexual history, illnesses, and injuries or surgeries that could affect fertility. 

Semen analysis

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. Because errors can occur in sperm collection and sperm counts can fluctuate, most doctors will check two or more semen samples over time to ensure consistency between samples.

Note that new sperm are produced continually in the testicles and take up to 2-3 months to mature. So, a current semen analysis reflects your environment over the past three months. Any positive changes you've made won't show up for several months.

Semen analysis results

Normal sperm densities range from 15 million to greater than 200 million sperm per milliliter of semen. Low sperm count is typically defined as fewer than 15 million sperm per milliliter or less than 39 million sperm total per ejaculate.

Other tests

Depending on initial findings, a provider might recommend additional tests to look for the cause of low sperm count and other possible causes of male infertility. These can include the following:

  • Scrotal ultrasound: an ultrasound to look at the testicles and supporting structures.
  • Hormone testing: a blood test to determine the level of hormones produced by the pituitary gland and testicles, which play a key role in sexual development and sperm production.
  • Post-ejaculation urinalysis: a urine sample to determine if sperm are traveling backward into the bladder instead of out your penis during ejaculation (retrograde ejaculation).
  • Genetic tests: a blood test to understand if there are subtle changes in the Y chromosome, which can indicate signs of a genetic abnormality. Genetic testing might also be ordered to diagnose various congenital or inherited syndromes.

The following tests are less common but may be performed in certain specific cases

  • Testicular biopsy: collecting samples from the testicle with a needle to look closely at sperm production. 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 affect their ability to function.
  • Specialized sperm function tests: several tests can be used to check how well your sperm survive after ejaculation, how well they can penetrate an egg, and whether they have a problem attaching to the egg. 
  • Transrectal ultrasound. A small lubricated wand is inserted into the rectum to check the prostate and check for blockages of the tubes that carry semen (ejaculatory ducts and seminal vesicles).

How is oligospermia treated?

The treatment suggested by a practitioner will depend on the cause of the oligospermia. In general, you may be able to increase your sperm count by stopping medications or behaviors that are contributing to low sperm levels. 

Other causes may require other approaches. For instance, surgery can treat a varicocele or blocked sperm ducts, or supplements may be prescribed to address hormonal concerns.

When to see a doctor

It is recommended to see a doctor if you have been unable to conceive a child after a year of regular, unprotected intercourse, or sooner if you have any of the following:

  • Erection or ejaculation problems, low sex drive, or other problems with sexual function
  • Pain, discomfort, or a lump or swelling in the testicle area
  • A history of testicle, prostate, or sexual problems
  • A groin, testicle, penis or scrotum surgery
  • Any other concerns or hesitations about fertility

How to Help Prevent Low Sperm Count

As discussed, low sperm count cannot always be prevented, but there are certain steps you can take to support sperm count and fertility. Avoid known factors that can affect sperm count and quality. For example:

  • Don't smoke.

  • Limit or abstain from alcohol.

  • Steer clear of illicit drugs.

  • Talk to your doctor about medications that can affect sperm count.

  • Maintain a healthy weight.

  • Avoid heat to the testicles.

  • Manage stress.

  • Avoid exposure to pesticides, heavy metals, and other toxins.

In addition, sperm health can be supported through targeted supplementation, including vitamins, minerals, omega-3 fatty acids, antioxidants, and botanicals. Needed’s collection of men’s fertility supplements are developed by experts, backed by clinical insights, and third party tested. They’re a powerful tool to add to your routine in support of sperm health.

Like the article? Share it!

Hillary Bennetts, Nutritionist

Hillary Bennetts is a nutritionist and business consultant focusing on prenatal and postpartum health. In addition to nutrition consulting, she provides business consulting and content creation for companies in the health and wellness industry. Hillary spent almost a decade in corporate consulting before shifting gears to combine her lifelong passion for health and wellness with her business background and nutrition education.