Sperm morphology refers to the size and shape of sperm. During a semen analysis, a laboratory examines sperm under a microscope and reports the percentage that meet strict criteria for normal appearance.

Normally shaped sperm have an oval head and a long tail. Abnormalities may involve the head, midpiece or tail.

Low sperm morphology, also called teratozoospermia, means that the percentage of normally shaped sperm is below the laboratory’s reference range. With strict criteria, a result below 4% normal forms is commonly considered low.

Does this mean infertility?

Not necessarily. A result of 3% normal forms does not mean you have only a 3% chance of pregnancy. Many sperm naturally do not meet strict shape criteria, and pregnancy can still occur with low morphology.

Sperm shape alone cannot reliably predict whether pregnancy will happen. Results should be reviewed alongside:

• Sperm count and concentration
• Sperm movement (motility)
• Semen volume
• Both partners’ reproductive health and fertility history

Your healthcare provider may recommend repeat testing or further assessment. One number does not tell the whole fertility story.