Teratozoospermia Types – Mild, Moderate & Severe

By (gynecologist), (embryologist) and (fertility counselor).
Last Update: 01/03/2024

Teratozoospermia or teratospermia is a sperm disorder that indicates the presence of a high percentage of abnormal or defective sperm.

It is a cause of infertility in males, and the level of severity varies depending on the number of amorphous sperm in the semen.

Based on a set of criteria to determinate the severity of teratospermia, it can be classified into 3 different degrees: mild, moderate, and severe. Despite the fact that with this seminal alteration it is complicated to achieve a pregnancy in a natural way, it does not mean that it is impossible.

Classification of teratozoospermia

When a man is referred to a semen analysis to determine his fertility levels, the report will indicate the results of multiple seminal parameters, including sperm morphology.

A sample is classified as teratozoospermic when the percent of sperm with normal morphology is below 4%, according to the guidelines published by the World Health Organization (WHO) back in 2010.

Although the World Health Organization (WHO) has published an update of the Laboratory Manual for Semen Examination and Processing in 2021 (the sixth edition), the most common practice is to continue to follow the criteria of the fifth edition (2010).

Also, some laboratories use Kruger's strict criteria to diagnose teratozoospermia. According to Kruger's, a man is teratozoospermic when fewer than 15% of sperm has an abnormal shape.

Since the reference value established by the WHO is so low, determining the types of teratozoospermia based on the amount of normal sperm is senseless. Thus, in order to classify abnormal sperm into mild, moderate or abnormal, the Kruger's criteria are more accurate than the WHO's.

Mild teratozoospermia

A man has mild teratozoospermia when the number of normal sperm present in his semen ranges between 14% and 10%.

The remainder of the sperm sample has some kind of abnormality in the head, neck, or tail. In spite of this, the prognosis of men with mild teratozoospermia is still a positive one.

Should Assisted Reproductive Technology (ART) be needed to have a baby, both Intrauterine Insemination (IUI) and In Vitro Fertilization (IVF) would be possible, depending on the sperm count and motility.

The shape of sperm is crucial for fertilization to be possible. However, the good news is that men with mild teratozoospermia can still achieve a natural pregnancy.

Furthermore, there exist vitamin supplements containing vitamins and antioxidants that can promote sperm maturation, thereby improving sperm morphology.

See also: Treatment of Choice for Teratozoospermia.

Moderate teratozoospermia

Moderate teratozoospermia is diagnosed when the semen analysis report shows than just 9 to 5% of sperm have a normal morphology.

Unfortunately, conceiving with moderate teratozoospermia is unlikely. Men with this type of teratozoospermia may need to turn to IVF/ICSI to have children.

ICSI (Intracytoplasmic Sperm Injection) involves selecting the sperm under the microscope in order to inject it directly into the egg to cause fertilization.

If you need to undergo IVF to become a mother, we recommend that you generate your Fertility Report now. 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.

If you wish to obtain more information about this assisted reproduction technique, we recommend you to visit the following article: Intracytoplasmic sperm injection: What is ICSI and how much is it?

Severe teratozoospermia

When the test to determine sperm morphology reveals that less than 5% of sperm have a normal shape, the sample is diagnosed with severe or serious teratozoospermia.

Sperm with good morphology are so few that the chances of achieving pregnancy naturally are considerably low.

The rationale for this is that sperm with such a poor morphology have trouble moving forward, which translates into trouble reaching the egg and penetrating the zona pellucida (egg coat) in order for the male and female nuclei to fuse together. As a result, fertilization failure occurs.

The treatment of choice when a man has severe teratozoospermia is ICSI or its improved version: IMSI.

The IMSI procedure is the same as the ICSI one, but the difference is that it uses a special lens for the microscope, which enables an increase greater than 6300-fold of spermatozoa. Thus, sperm morphology can be observed in detail, which allows the selection process to be improved.

FAQs from users

With what type of teratozoospermia is natural pregnancy possible?

By Alicia Francos Pérez M.D., M.Sc. (gynecologist).

Teratozoospermia is a seminal alteration characterized by problems in the morphology of the spermatozoa. It should be noted that most of the spermatozoa of a male have an altered morphology, since it is normal to have only 4% of spermatozoa with normal shapes.

There are several alterations in the morphology of the spermatozoa and their implication is different in the reproductive process. When the alterations appear in the head or the midpiece, there will be greater difficulty for fertilization. If what is altered is the tail of the spermatozoa, they will not be able to advance towards the egg.

Nevertheless, it is not impossible that a male with teratozoospermia cannot give rise to an evolutionary pregnancy, although it is true that it will be more complicated.
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Can severe teratozoospermia be cured?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

If the amount of normal sperm is fewer than 5%, the truth is that the chances for a natural pregnancy to occur are considerably low, and improving this situation with a natural remedy or medications is unlikely, too. Nonetheless, following healthier habits could improve it eventually.

On the other hand, if teratozoospermia is linked to other pathologies, such as varicocele, it is possible that the semen analysis report shows improved results after undergoing surgery to treat the varicocele.

What is isolated teratozoospermia?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Isolated teratozoospermia is defined as having less than 10% of normal forms, based on Kruger's strict criteria. A study published in 2003 showed that this type of teratozoospermia results in a lower cumulative birth rate compared to men with normozoospermia. (Spiessens C1, Vanderschueren D, Meuleman C, D'Hooghe T. Isolated teratozoospermia and intrauterine insemination, Fertil Steril. 2003 Nov;80(5):1185-9.)

Suggested for you

Depending on the type of teratozoospermia, that is, the degree of severity, a man may need to undergo fertility treatment to have children or not. To learn more, read: Achieving Pregnancy with Teratozoospermia.

The causes of teratozoospermia are varied and, more often than not, detecting them is a complicated process. If you are interested in delving deeper into this, do not miss this: What Are the Causes of Teratozoospermia?

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Auger J, Jouannet P, Eustache F. Another look at human sperm morphology. Hum Reprod. 2016;31(1):10-23 (View)

French DB, Sabanegh ES Jr, Goldfarb J, Desai N. Does severe teratozoospermia affect blastocyst formation, live birth rate, and other clinical outcome parameters in ICSI cycles? Fertil Steril. 2010;93(4):1097-103 (View)

Marchini M, Ruspa M, Baglioni A, Piffaretti-Yanez A, Campana A, Balerna M. Poor reproductive prognosis in severe teratozoospermia with a predominant sperm anomaly. Andrologia. 1989;21(5):468-75 (View)

Perrin A, Louanjli N, Ziane Y, Louanjli T, Le Roy C, Gueganic N, Amice V, De Braekeleer M, Morel F. Study of aneuploidy and DNA fragmentation in gametes of patients with severe teratozoospermia. Reprod Biomed Online. 2011;22(2):148-54 (View)

World Health Organization (WHO) (2010). WHO laboratory Manual for the examination of human semen and sperm-cervical mucus interaction. Cambridge Academic Press (View)

FAQs from users: 'With what type of teratozoospermia is natural pregnancy possible?', 'Can severe teratozoospermia be cured?' and 'What is isolated teratozoospermia?'.

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Authors and contributors

 Alicia Francos Pérez
Alicia Francos Pérez
M.D., M.Sc.
Alicia Francos has a degree in Medicine from the University of Salamanca and a Master's degree in Mastology and Breast Pathology from the Autonomous University of Madrid and another Master's degree in Human Fertility from the Complutense University of Madrid. She also has a diploma in Gynaecological Endoscopic Surgery from the Université Clermont Ferrand. More information about Alicia Francos Pérez
License: 330840199
 Zaira Salvador
Zaira Salvador
B.Sc., M.Sc.
Bachelor's Degree in Biotechnology from the Technical University of Valencia (UPV). Biotechnology Degree from the National University of Ireland en Galway (NUIG) and embryologist specializing in Assisted Reproduction, with a Master's Degree in Biotechnology of Human Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI) More information about Zaira Salvador
License: 3185-CV
Adapted into english by:
 Sandra Fernández
Sandra Fernández
B.A., M.A.
Fertility Counselor
Bachelor of Arts in Translation and Interpreting (English, Spanish, Catalan, German) from the University of Valencia (UV) and Heriot-Watt University, Riccarton Campus (Edinburgh, UK). Postgraduate Course in Legal Translation from the University of Valencia. Specialist in Medical Translation, with several years of experience in the field of Assisted Reproduction. More information about Sandra Fernández

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