Infertility is, as defined by The American Society for Reproductive Medicine, is a disease that results in the inability to conceive after one year of unprotected intercourse (or 6 months for women over the age of 35) or the inability to carry a pregnancy to live birth.
According to the Centers for Disease Control, 1 in 8 couples experiences infertility. While many people view the inability to conceive as an issue that lies primarily with women, the reality is that male infertility is just as likely a cause. This knowledge then begs the question: what causes male infertility? The answer is just as complex as the reproductive process itself.
Before we can effectively address the causes of male infertility, it’s important to know what must occur in the male reproductive system in order for the sperm to fertilize an egg. Here’s a quick overview:
- Healthy sperm must be produced
- Sperm must be mixed with semen
- There must be a healthy amount of sperm in the semen
- Sperm must be able to move normally
The Causes of Male Infertility
The main components of male infertility include abnormal sperm morphology, low sperm count, and poor sperm motility. These can be impacted by a variety of factors, ranging from health issues to sexual dysfunction to environmental causes. In order to accurately diagnose male infertility, he’ll need to see his primary care doctor or a fertility specialist for a blood test, semen analysis, or physical examination. Still, even before medical attention is required it can be helpful to understand the potential causes of infertility.
Abnormal Sperm Morphology
The morphology — or size and shape — of sperm is a critical component for fertility. Normal sperm has an oval head with a long, straight tail. Abnormal sperm can take a variety of shapes and sizes, including:
- Double head
- Double tail
- Crooked head
- Oversized head
Abnormal sperm may have difficulty reaching and penetrating an egg to fertilize it. There is much debate among professionals about what qualifies as healthy sperm morphology but one thing is agreed upon: all men have some abnormal sperm. What matters most is how much of your sperm is normal. According to the World Health Organization (WHO), the average amount of normal sperm morphology in men is 15%, with the cutoff for fertility coming in at 4%. This is good news when you’re trying to conceive — even with just 4% normal sperm, you’re considered fertile. Still, the more normal sperm produced, the higher the chances of conception.
Low Sperm Count
Oligospermia, otherwise known as low sperm count, can significantly decrease your odds of impregnating your partner. Though it only takes one healthy sperm to fertilize an egg, the more there are available, the higher your chances. The World Health Organization provides us with low, average, and high ranges of sperm count:
- Low sperm count — Though not considered infertile, the low end of sperm count is between 10 and 15 million sperm per milliliter of semen.
- Low-average sperm count — Sperm counts between 15 and 60 million sperm per milliliter of semen are considered to be still below average but not quite categorized as “low” sperm count.
- Average sperm count — The average range of sperm count needed to be conceived falls between 60 and 80 million sperm per milliliter of semen.
- High sperm count — If you have between 80 and 200 million sperm per milliliter of semen, you’re considered above average.
Here’s the thing, though. Even with low sperm counts, if you have exceptionally healthy sperm with great motility, you may have a higher chance of getting your partner pregnant than if you had high sperm counts but poor sperm morphology and motility.
Poor Sperm Motility
In order for your sperm to fertilize an egg, it must first reach the egg. This makes motility — or the sperm’s ability to swim — just as important as the morphology and count. Poor sperm motility, or asthenospermia, is diagnosed when around 40% of sperm does not make it past the vaginal canal.
Let’s take a look at the entire process of the sperm, in order to understand just how important motility is.
First, sperm production begins in coiled structures, called seminiferous tubules, that are located on the backside of the testicles. They then move to the epididymis, where they are stored while they mature. When the penis becomes erect and is stimulated, the mature sperm moves from the epididymis to the vas deferens and then past the prostate gland, where they mix with semen. From here, the mixture of sperm and semen travels through the ejaculatory ducts and out through the urethra. When this happens during sexual intercourse, the sperm and semen must then travel through the vaginal canal to the fallopian tubes, to meet the egg that is awaiting fertilization. Quite the process, right?
In order to reach the egg and fertilize it, sperm must be both fast and strong. So, even if you have a lot of sperm that has normal morphology, none of that matters if at least one of them can’t reach the egg.
What causes low sperm count, abnormal morphology, and poor motility?
As you can see, a lot of factors play into male fertility. Now that you understand the three main components of male fertility, let’s take a look at the factors that affect sperm count, morphology, and motility.
- Infections — Sexually transmitted infections, especially chlamydia, gonorrhea, and Mycoplasma, can impact the morphology of sperm. If you have a urinary tract infection, your body produces white blood cells (known as leukocytes) to fight off the bacteria. These white blood cells release a toxic substance that can damage sperm. The good news is that all of these infections can be treated with antibiotics, allowing your fertility to return to normal.
- Environmental exposure — Every day, you’re exposed to a variety of different toxins, chemicals, and substances that have the ability to affect sperm count, quality, and motility. These are known as endocrine disruptors and can be found in everything from household cleaning supplies to personal care products to food. Check out our article on male endocrine disruptors to learn more.
- Varicocele — Swelling of the veins that drain the testicles is known as varicocele and it the most common reversible cause of male infertility. It affects both the quality and quantity of sperm and is largely due to abnormal temperature regulation of the testicles.
- Genetic disorders — Sometimes, infertility has nothing to do with your environment or lifestyle. It can be related to a genetic disorder inherited from your parents. Some of these include:
- Cystic fibrosis — this common disorder cause your vas deferens (the tube that carries sperm) to be missing or obstructed
- Klinefelter syndrome — characterized by having 2 or more X chromosomes, this can cause lowered testosterone levels and abnormal seminiferous tubules
- Polycystic kidney disease — this causes growths on the kidneys and other organs and, if spread to the reproductive tract, can cause infertility
- Kartagener syndrome — though rare, this disease can cause problems with your airways and negatively impact sperm motility
- Hormone imbalances — Levels of testosterone, androgens, luteinizing hormone, and follicle-stimulating hormone all need to be at the right level. Too low or too high levels can cause male infertility. Though there are many underlying causes that can cause men to have hormonal imbalances, there are usually effective methods for treating them.
- Sexual dysfunction — If you have a hard time getting or maintaining an erection, it can be challenging to get your partner pregnant. Treatments are available for this, so be sure to talk to your healthcare provider.
- Celiac disease — An allergy to gluten, known as celiacs disease, can cause fertility issues in men and women. Though more research needs to be done, it is thought that men with celiac disease have abnormal hormone levels and sperm. Adopting a gluten-free diet may help.
- Medications — Though some medications may be necessary for your health and well-being, it’s important to discuss their impact on your fertility with your doctor. Chemotherapy medications, testosterone replacement therapy, and antifungal and ulcer medications can impair sperm production.
- Defect sperm transport tubules — The seminiferous tubules, epididymis, vas deferens, ejaculatory ducts, and urethra all play a large role in transporting sperm through and out of the male reproductive tract. If an injury, scarring from a surgery, or abnormal developments affect any of these tubules, sperm may have difficulty (or may not be able to) carry sperm.
- High fever or overheated testicles— In order to create healthy sperm, testicles need to stay slightly cooler than the rest of your body. Illness that results in a high fever can cause abnormal sperm production, as well as spending a lot of time in hot tubs, wearing tight underwear, or holding a laptop.
- Retrograde ejaculation — Normally, semen is released through the urethra. When retrograde ejaculation occurs, semen goes into your bladder instead. This happens when the muscle that helps you hold in urine fails to contract during ejaculation. There are several potential causes of retrograde ejaculation including diabetes, spinal cord injury, multiple sclerosis, and Parkinson’s disease.
- Lifestyle factors — There are so many components of male infertility that are not easily controlled. When it comes to your lifestyle, though, you can (usually) take action to help improve your fertility.
- Age — There’s not much you can do about your age but being aware that, as time goes on, your sperm count and quality tend to decrease can help you stay proactive about your fertility.
- Stress — Research has found that high levels of stress can negatively impact sperm quality and count.
- Weight — Excess body fat is often accompanied by a higher body temperature and hormonal imbalances. Even losing a small percentage of your body weight could help increase fertility.
- Alcohol, cigarettes, and drug use — Aside from being harmful to your overall health, the excess consumption of alcohol and any level of cigarette and drug use can cause the quality, count, and motility of your sperm to deteriorate.
Male infertility is no easy topic to tackle. There are many different factors that play into the production of healthy sperm, how much there is of it, and how well it moves from the testicles to an egg in a female’s fallopian tubes. Understanding the potential causes, and taking action where you can, can go a long way in making your journey to conception a bit easier.