Low Sperm Count Causes and Treatments

Overview of Oligoasthenoteratozoospermia (OAT)

Sperm approaching an ovum

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One of the primary causes of infertility is low sperm count and motility. These issues, coupled with poor sperm quality, represent 90% of all cases of infertility in men and anywhere from 20% to 40% in couples. This condition is called oligoasthenoteratozoospermia.

Nearly one in six men is affected by infertility related to problems with their sperm. The causes can range from hereditary factors and lifestyle choices to past infections and a person's age.

The term for low sperm count and motility is oligoasthenoteratozoospermia (OAT).

Sperm Abnormalities

The term oligoasthenoteratozoospermia, or OAT, is used when all three of the following factors are present:

  • An abnormally low level of sperm of a healthy shape (teratozoospermia)
  • An abnormally low amount of sperm (oligozoospermia)
  • An abnormally low amount of sperm with good motility (asthenozoospermia)

Idiopathic oligoasthenoteratozoospermia is used when the cause of the condition is unclear. Up to 30% of male infertility cases are said to have idiopathic OAT.

The factors for OAT can be broadly broken down into five categories: genetic factors, lifestyle factors, environmental factors, medical factors, and testicular factors. The treatment options available will depend on the cause of OAT.

Genetic Causes

Genetic factors can affect every stage of male fertility—from DNA damage in sperm cells (spermatozoa), genetic defects of the Y chromosome, and genetic disorders like Klinefelter syndrome, in which men have an extra X chromosome. While most genetic factors are not treatable, they can often be overcome with the use of in vitro fertilization (IVF).

Lifestyle Causes

Lifestyle factors involve both habits and conditions that directly affect the sperm. Many of these factors can be changed, and doing so can significantly improve a person's chance of conceiving.

Alcohol and Drug Use

As few as five drinks per week can significantly lower testosterone levels and sperm quality. Many recreational drugs have the same effect. Using anabolic steroids is also known to cause OAT.


Overheating the testes is associated with a low sperm count. Causes include taking very hot showers, baths, or saunas, as well as wearing tight briefs instead of boxers. A sedentary lifestyle and certain professions like being a cab driver or frequently sitting with a laptop directly on your lap can also lead to the overheating of the testicles.

Overexertion at the gym can also have the same effect. Typically, once the activity causing excess heat is stopped, sperm production returns to normal.


Smoking is strongly linked to male infertility although the reasons are not entirely clear. Smoking can reduce sperm count by 17.5% and sperm motility by 16.6%.

Strenuous Activities

Strenuous exercise like riding (cycling, horseback) can cause testicular inflammation. This can be relieved by simply taking a break from the activity.


Obesity and being overweight are known to cause hormonal changes that can directly impact fertility. Being underweight can also have a negative effect.

Environmental Factors

Exposure to environmental toxins can also cause low sperm count. Environmental factors that may adversely impact sperm counts include exposure to heavy metals and industrial chemicals. Some of the chemicals and metals that can decrease sperm counts are benzenes, dioxins, lead, herbicides, pesticides, painting materials, and organic solvents.

Medical Factors

There are a variety of medical issues that can cause OAT. These include injury, current or past infections, medications, and other medical conditions,

Medical Conditions

Some medical conditions like cystic fibrosis, celiac disease, tumors, hormonal imbalances, and cancer can impact sperm production. Problems with the immune system can cause antibodies that attack sperm. Other chronic health issues, such as diabetes, may cause erectile dysfunction. Sexually transmitted infections (STIs) can also impact male fertility.

Testicular Problems

Testicular factors can interfere with the testicle's ability to produce ample quantity or quality of sperm. Some of these issues can be treated but others cannot.

Examples of factors that can impact testicular function include:

  • Certain past infections (syphilis, mumps, malaria) that are known to either directly or indirectly affect the male reproductive system
  • Chemotherapy and radiation therapy
  • Older age
  • Past surgery or other medical procedures to the reproductive system
  • Testicular cancer
  • Testicular trauma
  • Varicocele, also called varicose veins of the scrotum, an enlargement and swelling of veins in the scrotum that can often be treated surgically and non-surgically

Testicular and Ejaculatory Dysfunction

Testicular and ejaculatory dysfunction refers to any condition that impedes the ability to ejaculate or obstructs the flow of semen in the male genital tract. These include:

  • Erectile dysfunction
  • Hypospadias, a congenital defect in which the opening of the urethra is not situated on the head of the penis
  • Obstruction of the vas deferens or ejaculatory duct
  • Prostatitis (inflammation of the prostate gland)
  • Retrograde ejaculation, where semen is inadvertently redirected to the bladder

Some of these can be treated with medication or surgical procudures.


Prescription drugs, including anabolic steroids and Tagamet (which is used to treat stomach acid), can also affect the quality of sperm. Other medications can affect sperm motility, These include Azulfidine, to treat rheumatoid arthritis, and Macrobid, to treat bladder infections.

Some other medications that can contribute to OAT include some antibiotics, antifungal drugs, medications to treat cancer, and ulcer drugs. Speak to your doctor about fertility-related side effects of any medications you are taking. There may be alternatives available.

A Word From Verywell

Many of the causes of male infertility can be treated. Even when they cannot be treated, there is an array of assisted reproductive procedures that can improve a couple's chance of conceiving. They include fertility drugs, medical devices, surgery, or a combination of treatments. 

If you are experiencing male infertility, speak with a fertility specialist. Whatever the cause, they might be able to help.

9 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Kumar N, Singh AK. Trends of male factor infertility, an important cause of infertility: A review of literature. J Hum Reprod Sci. 2015;8(4):191-196. doi:10.4103/0974-1208.170370

  2. Cavallini G. Male Idiopathic Oligoasthenoteratozoospermia. Asian J Androl. 2016;8(2):143-157. doi:10.1111/j.1745-7262.2006.00123.x

  3. Punab M, Poolamets O, Paju P, et al. Causes of male infertility: a 9-year prospective monocentre study on 1737 patients with reduced total sperm counts. Hum Reprod. 2017;32(1):18-31. doi:10.1093/humrep/dew284

  4. Sansone A, Di Dato C, de Angelis C, et al. Smoke, alcohol and drug addiction and male fertilityReprod Biol Endocrinol. 2018;16(1):3. doi:10.1186/s12958-018-0320-7

  5. Wu YQ, Rao M, Hu SF, Ke DD, Zhu CH, Xia W. Effect of transient scrotal hyperthermia on human sperm: an iTRAQ-based proteomic analysisReprod Biol Endocrinol. 2020;18(1):83. doi:10.1186/s12958-020-00640-w

  6. Kovac JR, Khanna A, Lipshultz LI. The Effects of Cigarette Smoking on Male Fertility. Postgrad Med. 2015;127(3):338-341. doi:10.1080/00325481.2015.1015928

  7. Hajizadeh Maleki B, Tartibian B. Long-term low-to-intensive cycling training: impact on semen parameters and seminal cytokines. Clin J Sport Med. 2015;25(6):535-40. doi:10.1097/JSM.0000000000000122

  8. Palmer NO, Bakos HW, Fullston T, Lane M. Impact of obesity on male fertility, sperm function and molecular composition. Spermatogenesis. 2012;2(4):253-263. doi:10.4161/spmg.21362

  9. Sharma A, Mollier J, Brocklesby RWK, Caves C, Jayasena CN, Minhas S. Endocrine-disrupting chemicals and male reproductive healthReprod Med Biol. 2020;19(3):243-253. doi:10.1002/rmb2.12326

By Rachel Gurevich, RN
Rachel Gurevich is a fertility advocate, author, and recipient of The Hope Award for Achievement, from Resolve: The National Infertility Association. She is a professional member of the Association of Health Care Journalists and has been writing about women’s health since 2001. Rachel uses her own experiences with infertility to write compassionate, practical, and supportive articles.