By Zaira Salvador BSc, MSc (embryologist) and Andrea Abbad BSc, MSc (embryologist).
Last Update: 04/06/2018

Teratozoospermia, sometimes called teratospermia, is defined as abnormal sperm morphology. It is a sperm disorder that causes males affected to produced abnormally shaped sperm.

The pregnancy rate in males affected by teratozoospermia depends on the grade of severity. It is considered a cause of male infertility, and its causes are varied or even unknown.

There exist various treatment options to have a baby with abnormal sperm morphology. The chances of success depend on the remaining sperm parameters, as teratozoospermia may be combined with other pathologies, like sperm count or sperm motility.


Teratozoospermia is the medical term used to refer to abnormal sperm morphology, caused by either defects in the head, midpiece, and/or tail.

According to the criteria published in 2010 by the World Health Organization (WHO), a man has teratozoospermia when more than 96% of the sperms he produces are abnormally shaped.

If at least 4% of sperms have a normal shape, the male is considered fertile and able to cause a pregnancy in a woman naturally.

The only possible way to examine the morphology of sperm is by means of a semen analysis or seminogram. To check the morphology, the specialist uses a dye test to see the shape of the sperms under the microscope.

Some laboratories use the Kruger’s strict criteria to evaluate a semen sample as well. In such cases, your report will contain a diagnosis based on both criteria.

In accordance with Kruger’s strict criteria, teratozoospermia is present when more than 85% of spermatozoa have an abnormal shape. As one shall see, this criteria is far stricter than the ones published by the WHO.

In other words, the borderline to consider whether a man has teratozoospermia or not is set at 15% of normal forms instead of 4%, which is the percent established by the WHO since 2010.

Unless otherwise specified in your semen analysis report, most clinics follow the WHO’s 2010 criteria when examining semen samples. Nowadays, the Kruger’s strict criteria are falling into disuse.


Teratozoospermia is associated with male infertility in all cases, as it means that sperm are unable to meet the egg due to their abnormal shape.

The causes of abnormal sperm morphology are varied and in most cases difficult to determine. The following are the most common ones:

  • Genetic traits
  • Cancer treatments (chemotherapy and radiotherapy)
  • Bacterial infections in sperm and orchitis
  • Testicular trauma
  • Testicular disorders, like varicocele
  • Fever
  • Diabetes mellitus (DM) or meningitis
  • Tobacco, alcohol and street drug use
  • Unhealthy habits: unbalanced diet, exposure to toxic substances, too tight clothes, etc.

The good news is that teratozoospermia can be cured in some of these cases. For example, if caused by fever, infections, or stress, the man is likely to start producing normal sperm again once these conditions disappear. If the cause is associated with unhealthy habits, picking up healthier habits such as following a balanced diet, quitting smoking, etc. can improve sperm quality.

Related content: Foods to Boost Sperm Quality.


Defects in the morphology of sperm can be classified into different types depending on their location—head, midpiece, and/or tail. However, before diagnosing teratozoospermia, all abnormalities are taken into consideration.

A sperm cell is considered normal if the head has an oval shape and contains an acrosome. The head and middle piece is slightly thicker than the tail or flagellum, which is a structure that connects to the head and middle piece.

You may also enjoy some further information reading this: What Is Sperm Morphology? – Meaning & Normal Range.

After examining sperm morphology with a semen analysis, it is possible for the specialist to determine the type of teratozoospermia and its grade of severity using Kruger’s strict criteria:

Mild teratozoospermia
Between 10% and 14% of sperm have a normal morphology.
Moderate teratozoospermia
The percentage of sperm with normal morphology ranges between 5% and 9%.
Severe teratozoospermia
Normal morphology is present in less than 5% of sperm.

As mentioned earlier, the criteria used to diagnose teratozoospermia are the ones published by the OMS. In other words, this classification has fallen into disuse. Some laboratories, however, still use them.

Teratozoospermia index

This parameter is used to identify the number of defects present in each sperm cell. It is possible for a sperm to have an anomaly in just one part, or in multiple areas.

To calculate the teratozoospermia index (TZI), we use the following formula: TZI = ( c + p + q ) / x, where each variable means:

  • c = head defects
  • p = midpiece defects
  • q = tail defects
  • x = total number of abnormal sperm

The TZI score should be interpreted as follows:

  • TZI close to 1: One part affected
  • TZI close to 2: Two parts affected
  • TZI close to 3: Head, midpiece and tail affected

It should be noted that all three types can be found in a semen sample, that is, with sperm cells that have defects in one, two or all three parts. The TZI indicates which type is the most frequent one.


A man with teratozoospermia can achieve a natural pregnancy as long as the remaining sperm parameters, particularly the sperm count and sperm motility, are normal.

Nevertheless, when a couple is trying to conceive with but a pregnancy never occurs, men can follow a series of medical tips in an attempt to improve the morphology of their sperms.

On the other hand, if teratozoospermia has a genetic origin or is present from birth (congenital), finding a treatment option that actually works may be harder.

Natural treatment

First of all, men with teratozoospermia should change their lifestyle and quit unhealthy habits for their organism, such as cigarette smoking or alcoholic drinks.

Following a balanced diet is always key when it comes to improving one’s fertility. Particularly, foods rich in antioxidants and essential amino acids like L-carnitine, which boosts sperm quality.

Oily fish is rich in omega-3 fatty acids as well, which is greatly beneficial for the reproductive health of males.

Also, all these vitamins and nutrients can be taken in the form of vitamin supplements like maca root powder or supplements containing vitamin E, which functions as a powerful antioxidant.

Fertility treatments

In case a fertility treatment is needed to achieve a pregnancy, Intrauterine Insemination (IUI) may be an option as long as it is a case of mild teratozoospermia, and sperm count and motility are normal.

IUI can be considered as the first choice only if the female partner doesn’t have fertility issues. In short, it is a treatment option when teratozoospermia is the cause of infertility in the couple.

On the other hand, in cases of moderate to severe teratozoospermia, or when there exists a combination of various sperm disorders, IVF/ICSI would be the treatment of choice. It is a type of IVF that uses a microinjection to insert the sperm cell directly into the egg cell, making sure that fertilization occurs.

If you need to undergo IVF to become a mother, we recommend that you use "The Calculator". In 3 simple steps, it will show you a list of clinics that fit your preferences and meet our strict quality criteria. Moreover, you will receive a report via email with useful tips to visit a fertility clinic for the first time.

Finally, there exists a cutting-edge technique that is similar to ICSI. It is called IMSI (intracytoplasmic morphologically selected sperm injection), and involves the use of a high magnification light microscopy imaging method to see sperm morphology in detail.

The microscope used in IMSI to select the best spermatozoon includes a lens for high magnification, which allows the specialist to see the potential defects that are present in each sperm cell in full detail.

Read: What Is Intracytoplasmic Morphologically Selected Sperm Injection (IMSI)?

FAQs from users

Can abnormal sperm morphology cause miscarriage?

By Zaira Salvador BSc, MSc (embryologist).

In principle, poor sperm morphology doesn’t lead to miscarriage once the egg has been fertilized and the embryo has attached to the womb. However, if the sperm contain a genetic abnormality, miscarriage is likely to occur.

Can abnormal sperm morphology fertilize an egg?

By Zaira Salvador BSc, MSc (embryologist).

Yes, as long as it is a mild case of teratozoospermia. In moderate or severe cases, techniques such as ICSI or even IMSI, in which the specialist inserts the sperm cell manually into the egg, would be needed.

What does 0 morphology mean?

By Zaira Salvador BSc, MSc (embryologist).

If the percentage of normal sperm is 0, it means that the man has severe teratozoospermia and the only possible way for him to conceive would be by using IVF/ICSI.

Learn more: What Is ICSI or Intracytoplasmic Sperm Injection?

What does teratozoospermia actually mean?

By Andrea Abbad BSc, MSc (embryologist).

The diagnosis of teratozoospermia means that the morphology of spermatozoa is altered and, for example, the head or the tail has an abnormal shape. Spermatozoa with an altered morphology cannot swim properly, which hinders their arrival to the Fallopian tube, where fertilization takes place. In case an abnormal spermatozoon reached the oocyte, it would not be able to fertilize it properly. Commonly, abnormal spermatozoa carry chromosomic abnormalities that, in case of fertilization, might lead into an altered embryo that will not implant into the uterus or lead to an early miscarriage. For these reasons, it can be difficult for a man to conceive naturally with teratozoospermia.

The good news is that abnormal spermatozoa can be removed from the sperm sample in the lab when it is prepared for an assisted reproduction technique. In any case, your doctor will evaluate all your fertility tests and decide which is the best option based on the severity of teratozoospermia. If the rest of the seminal parameters are normal, you will be able to use any technique.

Suggested for you

There exist other sperm disorders that can cause male infertility or at least complicate the TTC journey. Click here to learn more: Sperm Disorders that Cause Male Infertility.

A semen analysis is a method use by all andrology laboratories to evaluate sperm quality. To learn how it works and how to interpret the results, see this: What Is a Semen Analysis Report? – Purpose, Preparation & Cost.

If you are interested in getting further information about this male infertility cause, we recommend that you visit the following website: Teratozoospermia NET.

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Authors and contributors

 Zaira Salvador
BSc, MSc
Bachelor's Degree in Biotechnology from the Polytechnic University of Valencia (UPV). Embryologist specializing in Assisted Procreation, with a Master's Degree in Biotechnology of Human Assisted Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI). More information
License: 3185-CV
 Andrea Abbad
BSc, MSc
Bachelor's Degree in Biomedical Sciences from the Autonomous University of Barcelona (UAB). Master's Degree in Biology of Reproduction and Human Assisted Reproduction Techniques from the Institut Universitari Dexeus. Experience as an embryologist and fertility counselor. More information
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  1. Featured

    Is there any solution to sterility due to teratozospermia? I’m 36 and my wife and I have been trying to conceive for 2 years but no pregnancy yet… I did a seminogram and there was no sperm, I mean, my sperm count was zero. I couldn’t believe it so I did it twice, and still nothing. The thing is I had a problem on one of my testicles when I was a child and I underwent surgery, maybe is it linked to my infertility? I only beg you to clear my doubts, please.

    • Sandra FernándezBA, MA

      Dear Mark,

      The complete lack of sperm in the ejaculate is known as “azoospermia”. My recommendation is that you visit a fertility clinic so that an specialist determines whether it is a case of secretory or obstructive azoospermia. In the meanwhile, I invite you to visit to delve deeper into it.

      Good luck

  2. Featured

    I just want to know the severity of this morphology
    Head: 89%
    Neck: 7%
    Tail: 2%
    The Dr. said it’s a minor case and not that serious since we just married and TTC 7months only. She just give a multivitamins.
    But since we knew this diagnosis we never read a successful rate of conceiving. We are anxious and really worried but the Dr. says just keep trying and don’t feel stress. How should we acknowledge this condition?
    Thank You

    • Sandra FernándezBA, MA

      Dear hope,

      I’m afraid I cannot read it properly, as you didn’t post the percentage of total malformation. Do you have it written on your semen analysis report? I need it to know for sure whether it’s teratospermia or not.

      I’m sorry!

      Best regards