One in six people worldwide face infertility, and about 40% of infertility causes involve male reproductive health. When beginning the infertility journey, there tends to be a focus on female factors, but when you consider the initial goal of fertilization—and the many factors that can decrease the chances of sperm meeting egg—the significance of male infertility becomes evident.
Understanding and addressing male fertility issues is essential for couples navigating the complexities of infertility. In this article, we will walk through the biological process of fertilization as it relates to male fertility, examining the movement of sperm through the reproductive system, the chances of sperm meeting egg, and interventions that can enhance the odds of successful conception.
Male Factor Infertility and the Chances of Sperm Meeting Egg
Male fertility revolves around the health and function of the sperm. The smallest cells in the human body, sperm are quite simple—composed essentially of DNA and a “propeller” that enables them to move through the reproductive system. Difficulty conceiving is the result of any condition that hinders these cells from traveling through the body and fertilizing the egg. The treatment then for male infertility is simply to increase chances of sperm meeting egg.
What Affects the Chances of Sperm and Egg Meeting?
Various factors influence the chances of sperm meeting egg—from initial sperm production to the release and traversal of sperm through the female reproductive system. When diagnosing male infertility, we consider problems during production and maturation, barriers to movement out of the male reproductive system, and obstructions throughout the female reproductive system.
Production of Sperm
Before considering the chances of sperm meeting egg, we first have to ensure the presence of sperm in the male reproductive system. Sperm are produced in the testes, mature in the epididymis, travel through the sperm ducts, and are eventually released through ejaculation.
Sometimes there is an absence of sperm in the ejaculate. We refer to this as azoospermia, and it can either mean that sperm aren’t being produced by the testes (often due to hormonal imbalances) or that they are unable to travel through the epididymis or sperm ducts and into the semen.
Sperm & Ejaculation
Even if the sperm have successfully traveled through the sperm ducts, ejaculatory dysfunction can prevent them from leaving the male reproductive system. Issues like delayed ejaculation can impact the timing of sperm delivery, decreasing the chances of sperm meeting egg; or in the case of anejaculation or retrograde ejaculation, the complete inability to ejaculate can prevent the sperm from entering the female reproductive system at all.
Barriers in Sperm Traveling to Egg
Through natural intercourse, sperm must navigate through the vagina, cervix, uterus, and fallopian tubes to reach the egg. This is a long way to travel, and due to natural barriers like cervical mucus, many don’t make it. Any additional barriers make the chances of sperm meeting egg quite low.
Sperm Motility
A common type of male infertility is low sperm motility. When they have a defective “propeller”, it’s even more challenging for sperm to travel through the female reproductive system—especially in the presence of female infertility and issues like blocked fallopian tubes.
How Many Sperm Make It to the Egg
While an average of 200 million sperm are produced during ejaculation, only about 200 actually reach the egg. Starting out with an insufficient sperm count means that even fewer sperm will reach the egg, at which point they have to navigate several other barriers before actually fertilizing the egg. A person is considered to have a low sperm count with less than 20 million sperm.
What Happens When Sperm Meets Egg?
For conception to occur, sperm must not only reach the egg but also penetrate its protective layer. To penetrate the egg, the sperm must release enzymes that break down the egg’s protective barrier. While rare, some sperm may lack these enzymes and even when they’ve reached the egg, be unable to fertilize it.
While many sperm may reach and surround the egg, only one successfully penetrates, initiating the process of fertilization. When the sperm enters egg successfully, the egg undergoes biological changes to prevent other sperm from entering. This protective mechanism ensures the fertilization of only one egg, preventing complications such as multiple pregnancies.
Interventions for Increasing Chances of Sperm Meeting Egg
Fortunately, advancements in fertility medicine have allowed us to overcome nearly all male fertility problems; and with the right interventions, we are able to increase the chances of sperm meeting egg to counteract low sperm count, poor motility, and other obstructions to sperm travel.
Cutting The Distance
Proportionately speaking, the distance a sperm needs to cover within the female reproductive system is similar to the distance a fully grown person would need to swim to cross the Pacific Ocean. It’s no wonder then that so many millions of sperm don’t make it. And this is why, to increase the chances of sperm meeting egg, we often try to reduce the vast distance they have to swim.
Shortening the Distance with IUI
Intrauterine Insemination (IUI) offers one of the most effective ways to minimize the distance sperm need to travel and increase the chances of sperm meeting egg. This minimally invasive procedure involves collecting, washing, and placing sperm directly into the uterus during the female’s fertile window.
Increasing Chances of Sperm Meeting Egg with IVF & ICSI
In more extreme cases of male infertility, IUI may not be enough, as it still requires the sperm to travel some distance and penetrate the egg’s protective barrier. For sperm with very little to no motility, or other major functional issues, we can sidestep this final barrier through assisted fertilization using in vitro fertilization (IVF) in combination with Intracytoplasmic sperm injection (ICSI). Once the eggs have been removed from the ovaries, a single sperm is injected directly into a single egg, passing through the egg’s cytoplasm to initiate in vitro fertilization.
Bypassing Ejaculation Issues with Surgical Retrieval
Even when sperm are unable to travel through the male reproductive system or leave the body through ejaculation, conception is possible through advanced surgical techniques. Testicular sperm aspiration (TESA) and percutaneous epididymal sperm aspiration (PESA) allow use to retrieve sperm directly from the testes or epididymis and induce fertilization with IVF and ICSI.
Building a Family Despite Low Chances of Sperm Meeting Egg
With assisted reproductive technology, we can almost always help the sperm overcome barriers to meet and fertilize the egg. In rare cases when this is not an option—like when the male has never or is no longer producing viable sperm—intended parents have the option of building a family through alternative routes.
By using a sperm or embryo donor in conjunction with IUI or IVF, couples are able to start their families in spite of extreme or unexplained infertility—and even to experience the joy of conception and pregnancy without full biological connection.
There’s no doubt that navigating infertility is difficult and often very complex. In many cases, both female and male factors contribute to a couple’s collective infertility, and to find the best path forward requires attending to both partners’ reproductive health, potential barriers to fertilization, and the factors affecting the chances of sperm meeting egg.
Fortunately, with a complete diagnosis and comprehensive treatment plan, there is so much we can do to achieve a successful pregnancy. At the Idaho Center for Reproductive Medicine, we offer thorough diagnostic testing for both male and female partners to inform the most effective fertility treatment.
If you think male factors may be contributing to your infertility, we can help you find answers and pave a path forward for your growing family.
