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.