Sperm morphology: what is it, and how does it affect fertility?

Sperm morphology, or the shape of the sperm cells, is one of the things tested during sperm analysis that can affect your fertility. While it may be surprising to learn, most sperm cells even in a healthy sample may have irregular morphology. Keep scrolling to learn about normal sperm morphology, how it might be affecting your fertility, and what you can do to keep your sperm shape healthy. 

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Sperm morphology refers to the shape of individual sperm. 

Sperm cells are made up of three different parts: the head, neck, and tail. Each part has its own “ideal” shape and number and laboratory evaluation for sperm analysis involves examining a subset of the sperm in the sample to count how many have the right number of heads and tails and what percentage have the right shape, structure, and length. 

While the exact percentage of “perfect” sperm needed to consider it healthy may vary from one lab to another, you might be surprised to learn that anything upwards of 4% normal sperm morphology is typically considered to be sufficient for fertility. Keep in mind, of course, that there are many factors that can contribute to a person’s ability to conceive, so sperm morphology on its own isn’t going to determine whether or not you can have a baby. 

Sperm cells have three main parts: the head (the round part that contains the genetic material from dad), the neck, and the tail (which the sperm cell relies on to reach the egg in the female reproductive tract). 

According to the World Health Organization (WHO), sperm cells with normal morphology should have:

• One smooth, oval-shaped head that contains the genetic material (DNA). 

• One slender neck that extends from the head and continues to the tail. 

• One single tail (also called a flagellum) that’s thinner than the neck and is about 10 times as long as the sperm head. 

Sperm cells are considered abnormal when one or more of these characteristics are missing or less than ideal. For example, an abnormal sperm cell may have a double tail or a misshapen head. And as we mentioned, most samples have lots of irregularly-shaped sperm. What matters is that you have enough sperm with normal morphology so that one is able to swim to and fertilize an egg. 

Keep in mind that not every sperm cell in a sample is examined (there are millions of sperm cells in a typical sample and that would take ages). Instead, the lab will examine a subset of the sample and draw conclusions about the sample as a whole.

In general, sperm analysis can be a bit of a subjective science, meaning that the same sample analyzed by two different labs (or two different people at the same lab) might have slightly different results. 

But there are lots of efforts to standardize collection and analysis methods to give consistent results. Overall, labs typically report that for a sample with a normal morphology above 4%, the morphology shouldn’t have drastic effects on a person’s ability to conceive. The WHO has established parameters for morphology that work like this:

• If over 14% of sperm in a sample have normal morphology, the morphology likely isn’t affecting fertility. 

• If 4–14% of sperm in a sample have normal morphology, the morphology may be slightly decreasing fertility

• If less than 4% of sperm in a sample have normal morphology, research has found that the morphology may be having significant impacts on fertility. 

Keep in mind that even a normal morphology under 4% isn’t the end of the line when it comes to making a baby, though. You just need one healthy sperm cell to fertilize an egg, and while problematic morphology might be affecting your ability to conceive without assistance, there are many treatments available today that can improve your chances of having a baby.

Proper sperm shape is important for fertilization. If the head of the sperm isn’t shaped properly, it can hinder the sperm cell’s ability to fuse with the egg. If a sperm’s tail is abnormal, it may not be as effective at propelling itself toward an egg along the long journey through the female reproductive tract. 

Other sperm parameters

Morphology is not the only factor that can impact semen quality. There are many different sperm parameters as well as a range of other factors that can affect a person’s ability to conceive. Male fertility also depends on other characteristics, including 

• Sperm count, or the total number of sperm in the sample.

• Sperm motility, or the ability of sperm to move properly

• Semen volume, or the volume of the fluid a person ejaculates.

Additional factors that can affect fertility include whether or not a person has any genetic problems with their sperm cells, as well, of course, as their partner’s fertility. 

Sperm morphology testing is typically performed when a healthcare provider has concerns about fertility issues (like if you’re trying to conceive for an extended period of time without success). That said, sperm morphology is also examined before sperm storage for people undergoing procedures that may affect their sperm quality (such as radiation or chemotherapy for cancer or before a vasectomy). 

While collection of the semen sample for analysis has traditionally been done by masturbating into a cup at a doctor’s office, there are alternative options now, including at-home collection of a semen sample. This option is just as safe but offers the added benefits of being discrete, convenient, and more comfortable, as well. 

If you’ve received a sperm testing result with abnormal sperm morphology, there may be things you can do to improve morphology:

• Stop smoking: Cigarette smoking can damage sperm shape and motility, so cutting back on tobacco may improve your sperm quality. 

• Reduce alcohol consumption: Alcohol can harm sperm morphology and motility and decrease semen volume, so reducing alcohol intake may improve these parameters. 

• Consider weight loss: Obesity and metabolic syndrome can have an effect on a range of different body systems, and the reproductive system is no exception so if you have obesity, weight management can help improve your sperm health.

• Exercise: Some studies suggest that regular physical activity is linked to better sperm morphology, though the data is not conclusive.  

• Talk to your healthcare provider about supplements: There’s some evidence that nutritional supplements, like Vitamin E and selenium, may improve semen quality and sperm morphology, though not all experts agree. 

Things that probably won’t help? There’s always a little buzz in the media about the detrimental effects of cell phones on everything from our bank accounts to our mental health, but sperm morphology probably isn’t one of those things. Research has yet to clearly show that a cell phone in your pocket has any effect on your sperm morphology, though it may still have an impact on your sperm DNA—a parameter no less important when it comes to sperm health and fertility.  

Luckily, when it comes to sperm morphology, seemingly low numbers are typically actually normal in range (as we mentioned before). That means that as long as ~4% of your sperm have normal morphology, it shouldn’t affect your ability to conceive. 

But if your numbers are lower than that, intervention may be necessary to help with having a baby. Your best bet is to visit with a fertility specialist to understand exactly how these parameters may be affecting your ability to conceive and make a plan for getting pregnant.

Not all people with abnormal sperm morphology will experience infertility, and some people with abnormal sperm morphology can conceive without intervention. 

If you do experience infertility, there are several assisted reproductive technologies (ARTs) that may help, including 

• IUI (intrauterine insemination): With IUI, a healthcare provider injects sperm directly into the uterus, so it doesn’t need to travel far to reach an egg. Studies show that this procedure may be effective in people with reduced sperm morphology measurements. 

• IVF (in vitro fertilization): With IVF, sperm cells and eggs are combined outside the body before inserting the fertilized egg into a uterus.  

• ICSI (Intracytoplasmic sperm injection): For people with significant morphology issues, ICSI, can be a more effective solution than regular IVF. In this procedure, a single favorable sperm cell is selected and injected directly into an egg, which can then be implanted into a uterus. 

If you’ve been told that you have abnormal sperm morphology, remember that while sperm morphology contributes to fertility, abnormal sperm morphology doesn’t always mean you can’t fertilize an egg. 

There are things you can do to improve your sperm morphology and a range of interventions healthcare providers can use to help you conceive if you and your partner are experiencing infertility. Your healthcare provider can advise you on the best treatment options. 

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

February 06, 2023

Written by

Gina Allegretti, MD

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.