Sperm Morphology

Male Infertility

Dr. Suman

Aug 05, 2021

Sperm morphology refers to the shape of your sperm, or how it looks under a microscope. Specifically, it looks at the size of the sperm and the shape of the sperm head. The shape of the head is important as it affects the ability of the sperm to dissolve the outer surface of an egg and fertilize it. 

If you have been diagnosed with sperm morphology issues, then you must be having so many questions in your mind: what exactly does it mean? How does it affect my fertility? What can I do about it?

Read on to know more about sperm morphology. 

What is sperm morphology?

Morphology of Sperm refers to the shape of the sperm, which includes head size and head DNA content, the appearance of the midpiece, and the structure of the tail. The head shape is quite important as it can affect the sperm’s ability to penetrate the outer surface of a woman’s egg to fertilize it.

At the time of routine semen analysis, sperm morphology is assessed wherein sperm cells are examined under the microscope. The semen analysis also examines the motility and concentration of the sperm.

Every male, fertile or infertile, has a varying percentage of abnormally shaped sperm. There are several factors leading to abnormally shaped sperms such as increased testicular temperature, infection, exposure to toxic chemicals, and genetic traits. When a man has a large number of abnormally shaped sperm it is medically known as teratozoospermia or teratospermia. 

The World Health Organization also published their own sperm analysis criteria.  As of the 2010 study, as per WHO presence of 4 percent and higher sperm having normal morphology is considered ideal sample composition for fertility.  

Types of Sperm Morphology

Here let’s talk about types of sperm morphology. 

Normal shaped sperm: A normal sperm has an oval-shaped head, an intact midpiece, and an uncoiled single tail. A normal morphology sperm can swim well and in a straight line. Normal sperm consists of healthy genetic information instead of having too many or too few chromosomes, which are usually present in abnormally shaped sperm.

Macrocephaly Sperm: Macrocephaly refers to when the sperm has a giant head. In these types of sperm extra chromosomes are there and they face problems fertilizing the woman’s egg.  Usually, macrocephalic sperm is caused due to homozygous mutation of the aurora kinase C gene. It means this kind of sperm may be genetically abnormal, so fathers may be able to pass the condition on to their sons.

Microcephaly: Microcephaly, also known as small head sperm. In this, the sperm’s head is smaller than normal. These sperms may have defective acrosome or reduced genetic material.

Pinhead sperm: It is a variation of the small-head sperm. Here the head appears as a pin ranging from minimum to no paternal DNA content. The presence of this type of sperm may point to a diabetic condition.

Tapered head sperm: These types of sperm are known to have “cigar-shaped” heads indicating the presence of varicocele in the male or constant exposure of the scrotum to high-temperature locations like a daily hot sauna. Usually, these tapered head sperm consist of abnormal chromatin or packaging of the paternal DNA genetic material. In the tapered head sperm, an abnormal number of sperm chromosomes also known as aneuploidy is seen. 

Thin head sperm: Thin head sperm is an extreme variation of tapered head sperm with different pathologies from tapered head sperm. These sperm are rarely identified and due to broken DNA, varicocele, or disrupted head formation.

Decondensing head sperm: Roundhead sperm condition also known as Globozoospermia is known to be abnormal sperm morphology. It indicates that either acrosome is absent in it or the sperm is missing the inner part of its head that is responsible for activating the egg and initiating the fertilization process. Decondensing head sperm is the variation of this type of sperm and it is seen when the sperm prematurely starts to break down its nucleus besides the unraveling DNA material is filled in the entire sperm head.

Headless sperm: This type of sperm has no head at all and is known as acephalic sperm or decapitated sperm syndrome. They lack genetic material or chromosomes. It may look like a pinhead sperm but when closely examined one can see that there is no tiny head and it gives the sperm an appearance of a loose piece of string.  

Tail-less sperm: Tail-less sperm are also known as acaudate sperm. Often these sperm are seen at the time of necrosis, the death of most or all of the cells in an organ.

Nuclear vacuoles sperm: These types of sperm have two or more large vacuoles (cyst-like bubbles) or sometimes multiple small vacuoles in the sperm head. They are visible under high magnification microscopy. As per some studies this type of sperm has low fertilization potential, whereas other studies show there is no effect. 

Multi-head sperm: Multiple parts sperm can have many heads or tails. When the sperm has two heads it is known as duplicate sperm. It is a condition linked to exposure to toxic chemicals, heavy metals such as cesium, smoke or high prolactin hormone in the male.

Thick, swollen neck: Large swollen midpiece or sperm neck can be due to defective mitochondria, the sperm’s energy making parts. It may also be a sign that the centrioles, the guidance system for moving chromosomes that are stored at the neck of the sperm, may be missing or broken.

Coiled-tail sperm: These types of sperm are usually exposed to either incorrect seminal fluid conditions or bacterial presence. Due to damaged tails, these sperm cannot swim. Heavy smoking is liked to coiled-tails perm.

Stump-tail sperm: Sperm cells with short tails usually have low or no motility and are known as stump tail sperm or Dysplasia of Fibrous Sheath (DFS) sperm. This defect occurs during late spermiogenesis or sperm cell formation in the testis.   Some patients with DFS also have a chronic respiratory disease associated with immotile cilia syndrome. Stump tail or DFS is known to be an autosomal recessive genetic disorder associated with abnormal genes encoding for proteins like the sperm neck centrin 1 protein. It is known that DFS is linked to a higher percentage of sperm aneuploidies or abnormal chromosomes.  

What are sperm morphology ranges?

Sperm morphology ranges let you known what percent of sperm are considered normal in size and shape. These sperm are able to fertilize the egg, so with the help of these percentages, you will be able to give a clue regarding your chances to conceive with your partner. Depending on lab to lab and the criteria used to assess the sperm, the ranges differ. When used stricter criteria it will result in the lower normal range.

The doctor will discuss your range with you and help you determine what effect it will have on your fertility. According to Dr. Jane Frederick, a leading board-certified reproductive endocrinologist in Orange County, “There are different ranges for morphology depending on the lab, but we use a strict Kruger morphology that means 14 percent or more is normal sperm morphology range. Ten to 14 percent is still good fertility potential, 5 to 10 percent is decreased fertility, and less than 5 percent is poor fertility potential.” 

How is sperm morphology assessed?

Sperm morphology is assessed, by examining the sperm under a microscope and getting the estimate of abnormally shaped sperm. It is imperative to know that all men produce abnormal sperm and mostly half of the sperm in a ‘normal’ semen sample are abnormally shaped. 

2 sets of characteristics are used to assess sperm morphology. Kruger criteria are strict and take minute irregularities as abnormal. World Health Organization (WHO) criteria are a bit lenient and thus do not classify as many sperm as abnormal.

There are times when morphology is used to decide whether a couple should go for in vitro fertilization (IVF) to conceive. It is best to consult your doctor to know which method is used to assess sperm and the significance of the results. 

Thus, with the help of these ranges, you can know the sperm morphology normal range.  

Sperm Morphology’s Effect on Fertility

The most common cause of male infertility is low sperm count, and its shape also plays a role. Morphology can affect fertility as sperm needs a particular shape to be able to penetrate through the outer layer of the egg. 

Most of the men with abnormal sperm morphology are still able to fertilize an egg, but conceiving can take a long time or may also need assistance from a fertility specialist. 

For those with sperm morphology issue intrauterine insemination (IUI) or in vitro fertilization may be an option. To enhance the chances intracytoplasmic sperm injection (ICSI) can be used along with IVF. In some researches, it is also shown that taking antioxidants for male fertility supplements for three or more months can improve abnormal sperm morphology.

During IVF and ICSI the lab chooses a sperm with high chances of success, based on morphology and motility. This sperm is directly injected into a woman’s egg. Once the sperm fertilizes the egg and forms an embryo, it will be implanted into the woman’s womb when it is developed well.  

Can an abnormally shaped sperm fertilize an egg?

Yes an abnormally shaped sperm can fertilize an egg. However, in some studies, a higher amount of abnormally shaped sperm has been associated with infertility. Usually, if the number of abnormally shaped sperm is higher it may be associated with other irregularities of semen like low sperm count or motility. Men having abnormally shaped sperm may have no trouble causing pregnancy. 

How to improve sperm morphology?

The younger you are the healthier your sperm is. Some doctors even recommend freezing your sperm earlier in life, so that when you are ready to start a family you can have your healthiest sperm for use. If you have got to know that your sperm morphology range is low then you are too late for the option. 

Your body is always producing new sperm, thus changes in your diet and or lifestyle can have an impact on your future sperm. Here are some of the ways to improve your sperm morphology:

  • Exercising regularly
  • Losing weight
  • Wearing loose cotton boxers
  • Avoiding heavy drinking, illegal drugs, use of tobacco

Some vitamins and supplements may be beneficial for promoting normal sperm morphology.

Treatment for Sperm Morphology to Get Pregnant

There are some options available to consider when it comes to sperm morphology treatment to get pregnant:

Sperm Washing

Sperm washing is a procedure of removing low-quality sperm and mucus from semen to enhance the chances of pregnancy. It is known as a part of several fertility procedures. 

Intrauterine Insemination (IUI)

In this type of artificial insemination, sperm is directly placed inside the woman’s uterus. This bypasses some of a woman’s anatomy, thus enhancing chances of successful pregnancy even when the male factor infertility issue is there.

In Vitro Fertilization (IVF)

In IVF procedure fertilization of an egg is carried out in the lab and later the fertilized embryo is placed inside a woman so that it can be carried to term. This increases the chances of pregnancy. 

Intracytoplasmic Sperm injection (ICSI)

Usually, ICSI is used as a part of the IVF process. In this process, sperm is directly injected into the cytoplasm of the egg and it helps in improving chances of fertilization and pregnancy.

Sperm Donation

Sometimes it is good to rely on donor sperm, which is healthy and of good quality. There is an option to select sperm donors via appearance and personality profile to make sure a good match and a great chance of treatment success. 


Many people are familiar with the role of sperm count in fertility, yet sperm morphology is another important factor. Sperm morphology refers to the appearance, shape, and anatomy of a man’s sperm. Healthy sperm have a normal shape and can swim properly which aids in the fertilization process. 

There are different types of sperm morphology and ranges of sperm morphology help you to know the percent of sperm is considered normal in shape. Depending on sperm morphology there are several treatment options available.  


How to get pregnant with poor sperm morphology?

Men having abnormal sperm morphology are still able to have children, but achieving pregnancy may take longer or may also need assistance from fertility specialist. Intrauterine insemination (IUI) or in vitro fertilization (IVF) may be an option for those with sperm morphology issues.

What is the normal morphology of sperm?

Usually the precise range varies, but the normal or healthy sperm morphology range is between 4 and 14 percent NF. If the score is below 4 then it means that it may take longer than normal to achieve pregnancy. If the result is 0 percent NF then it usually means, for conception in vitro fertilization may be needed.

What is IUI sperm morphology?

As per several studies it is found there is a strong correlation between sperm morphology and the IUI result. In assessing sperms morphology by strict criteria, success rates with IUI are highest when 14% or more of the sperm have normal morphology.

What causes poor sperm morphology?

The causes of poor sperm morphology can be due to environmental condition, work-related exposure, and lifestyle choices. For instance, overheating testicles (from frequent hot tub use), toxic chemical exposure at work, obesity, smoking, and recreational drug and alcohol use can reduce sperm counts.

Does caffeine affects sperm morphology?

There is no association between caffeine and sperm morphology. It is seen that men with high caffeine intake had about 14% higher concentration of testosterone compared to men with low caffeine intake.   

How to correct sperm morphology?

Most of the fertility specialists recommend Vitamin D supplements to improve the overall health of sperm, including morphology, concentration, and motility. 


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