Teratospermia, more precisely teratozoospermia, means the proportion of sperm meeting strict normal-shape criteria is below the reference range. WHO 2021 uses about 4% normal forms as the lower reference value. Because morphology assessment is deliberately strict and somewhat observer-dependent, an isolated low percentage should not be treated as a direct measure of genetic quality or as proof that natural pregnancy cannot occur.

This page focuses on the medical term teratospermia and how morphology is reported. For a broader patient guide to isolated low morphology, common misconceptions and treatment decisions, see ‘Poor Sperm Morphology: What It Means.’

What is Teratospermia?

Teratozoospermia is a semen-report term for low normal morphology. It is not the same as having “deformed genetic material.” Morphology looks at the visible shape of the sperm head, midpiece and tail under standardized criteria.

How to understand the report

Common reasons

• Natural biological and observer variation.
• Varicocele.
• Fever or illness.
• Smoking and oxidative stress.
• Heat and environmental exposures.
• Broader testicular dysfunction when count and motility are also low.
• Rare genetic morphology syndromes in selected severe patterns.

What tests may be needed

If morphology is the only abnormal parameter, review the laboratory method and repeat the semen analysis when clinically appropriate. A specific uniform defect or severe combined semen abnormality deserves andrology review. Routine genetic testing is not required for ordinary isolated teratozoospermia.

Treatment and fertility options

There is no specific tablet that reliably normalizes sperm morphology. Address reversible factors, treat a clinical varicocele when standard indications are met, and choose natural conception, IUI or IVF/ICSI based on the full semen profile and female factors rather than morphology alone.

When teratospermia needs specialist review

• A very low morphology percentage persists and infertility continues despite otherwise appropriate timing and evaluation.
• The report describes a near-uniform sperm-shape defect rather than the common mixed abnormalities seen with strict morphology assessment.
• Morphology is low together with reduced concentration or motility, making the overall semen abnormality more clinically important.
• There is a clinical varicocele, abnormal testicular examination, previous testicular disease or fertility-suppressing hormone use.
• Previous IVF/ICSI showed poor fertilisation or the embryology team identified a morphology pattern that may affect counselling.

When should morphology be rechecked?

Morphology has meaningful observer and laboratory variation, so a small percentage change should not be overinterpreted. In a stable situation with an abnormal first analysis, the WHO 2025 infertility guideline suggests repeating semen testing after a minimum of about 11 weeks. A suspected uniform morphology syndrome or a severe combined semen abnormality should be evaluated sooner rather than left to repeat testing alone.

Isolated teratospermia versus a specific morphology syndrome

Most men with a low morphology percentage have a mixture of different sperm-shape abnormalities. In that situation, the number is interpreted with concentration, motility and the couple’s fertility history. A mildly low isolated morphology value is not equivalent to a severe combined semen abnormality.

A uniform defect affecting nearly every sperm is different. Examples include globozoospermia, in which sperm heads lack the normal acrosomal structure, and rare macrozoospermia patterns. These situations may carry specific fertilisation or genetic implications and deserve specialist review. They should not be confused with the common report of 1-3% normal forms using strict morphology criteria.

Morphology also has more observer and laboratory variation than many patients realise. When morphology is the only abnormal parameter, comparing results from the same quality laboratory can be more informative than reacting to a small percentage change between different laboratories.

For follow-up, a change from 2% to 3% should not be overinterpreted as a dramatic biological improvement. Small percentage differences can reflect sampling and observer variation, so the entire semen profile and the couple’s outcome matter more than a single morphology digit.

What to bring for consultation

Bring these if available:

• Semen reports with the morphology percentage and the laboratory method/reference used.
• Previous reports for comparison, ideally including concentration and motility from the same samples.
• Any report describing a specific uniform sperm-shape defect rather than simply a low percentage of normal forms.
• Scrotal Doppler/hormone reports and history of fever, varicocele, testicular disease or steroid/testosterone use.
• Previous fertility-treatment/embryology records and the partner’s fertility evaluation if relevant.

FAQs

Related reading

• Poor Sperm Morphology: What It Means
• Semen Analysis Report Explained
• Oligoasthenoteratospermia Explained
• Varicocele and Male Infertility
• Lifestyle Changes to Improve Sperm Count
• Urologist in Latur

References

• World Health Organization. WHO laboratory manual for the examination and processing of human semen, 6th ed https://www.who.int/publications/i/item/9789240030787
• World Health Organization. Guideline for the prevention, diagnosis and treatment of infertility. 2025 https://www.who.int/publications/i/item/9789240115774
• European Association of Urology. EAU Guidelines on Sexual and Reproductive Health: Male Infertility. 2026 https://uroweb.org/guidelines/sexual-and-reproductive-health/chapter/male-infertility
• American Urological Association/American Society for Reproductive Medicine. Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline (2020; Amended 2024) https://www.auanet.org/documents/Guidelines/PDF/2024%20Guidelines/Male%20Infertility%20Unabridged%20Final.pdf