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Last revised April 1, 2021

The hormones that drive male fertility

Hormones help regulate systems in the human body, like digestion, metabolism, mood, stress, and even reproduction. Sometimes, even minor changes in our hormones—and the balance between them—can have an impact on your body’s processes. Here, we'll cover the hormones that drive male fertility.

How do hormones affect male fertility?

There are many hormones that play a role in your fertility. Some hormones may have an indirect effect, such as testosterone—a testosterone deficiency may not affect sperm health, but can cause low sex drive or erectile dysfunction.

There are also two male fertility hormones that have a direct impact on sperm production. An imbalance or deficiency in one of these may have a negative impact on sperm quality parameters like count, concentration, morphology, and motility.

The 3 key male fertility hormones

These three male fertility hormones are crucial to driving the process of sperm production. They are balanced against one another; an imbalance in one hormone can create an imbalance in another. The right balance of all three is necessary for health sperm and optimal male fertility.


If you're familiar with any male fertility hormones, you probably know at least a little bit about testosterone or “T.” It’s the quintessential “male hormone,” though both male and female bodies produce and require T. Testosterone is responsible for the creation and growth of male sex organs (the penis and testes), and for the development of secondary sex characteristics during puberty, such as muscle growth, body hair, and a deeper voice.

Testosterone is produced within the testicles, by cells called Leydig cells. Testosterone is essential for some aspects of the process of creating sperm, known as spermatogenesis; specifically, it drives the division and differentiation of sperm cells.

Testosterone imbalance and male fertility

Low testosterone is known as hypogonadism, and may be caused by age or lifestyle factors. Many people assume that having low testosterone levels negatively impacts fertility, but that's not always the case. Testosterone is not the hormone that actually stimulates sperm production, and many men with low testosterone can still produce healthy sperm.

On the other hand, many believe that increasing your levels of testosterone, such as through testosterone replacement therapy (TRT) or anabolic steroids, will improve male fertility. However, testosterone therapy is known to decrease follicle-stimulating hormone (FSH), an essential hormone for stimulating sperm production. Research shows that testosterone treatment impairs sperm production.

Testosterone treatment is so impactful on sperm production that it’s actually been studied for use as a contraceptive. In one study that observed 271 healthy, fertile men injecting testosterone over a 12-month period, 65% developed azoospermia, or a condition in which you have no sperm in your semen. Even after testosterone injections were stopped, it took nearly four months for most of the men to return to normal baseline sperm levels. Similarly, long-term use of anabolic steroids is associated with drastically lower percentages of motile and morphologically normal sperm, often reaching zero sperm count—and in some cases this damage has been irreversible.

Although there's overwhelming evidence that testosterone therapy negatively impacts fertility, there was a fourfold increase of use in men 18–45 years old from 2003 to 2013. Doctors strongly advise men who would like to conceive in the future to avoid taking any form of testosterone treatment.

Follicle-stimulating hormone

Follicle stimulating hormone (FSH) is key to spermatogenesis. This hormone works closely with luteinizing hormone (LH) to produce sperm in the testes. Specifically, FSH is responsible for the function and maturation of the Sertoli cells, which are somatic (non-reproductive) cells in the testes that are essential for sperm production. FSH is produced in the pituitary gland, a small gland in the brain that’s responsible for producing hormones that drive many crucial functions of the body.

FSH imbalance and male fertility

Because of the big role that FSH plays in sperm production, low FSH can have serious consequences for sperm quality. FSH deficiency can be caused by the use of exogenous testosterone (as described above), an injury to or tumor in the pituitary, or a genetic mutation. 

FSH therapy is sometimes recommended to treat male infertility. In a study that followed 354 men affected by low sperm count with unknown cause, sperm count was significantly increased after three months of FSH treatment. Improvements in sperm morphology and motility was also observed after five months of treatment. Although studies have shown success with FSH treatment, it is still unknown exactly what dose of FSH or treatment method has the most success for male fertility.

Luteinizing hormone

Luteinizing hormone (LH) is responsible for testosterone production in the testes. Specifically, LH stimulates the Leydig cells in the testes, which produce the testosterone that will help support sperm production. Like FSH, LH is produced in the pituitary gland.

LH imbalance and male fertility

Similarly to low FSH, low LH can be caused by problems with the pituitary gland or excessive testosterone. Because LH drives the production of testosterone in the testes, a deficiency in LH can create a deficiency in testosterone, potentially impacting sex drive as well as fertility.

On the flip side, levels of LH or FSH that are too high could indicate testicular failure or damage. Both hormones are produced in the pituitary. If spermatogenesis is not proceeding as normal in the testes, the pituitary will go into overdrive, producing more LH and FSH.

Learn more about male fertility.

Other important male fertility hormones

Along with the three key hormones that impact sperm production, there are other hormones that can impact male fertility. While they don't directly affect sperm production, they still play a role in your fertility and overall sperm health.


Although estrogen is commonly known as a "female" hormone, it is present in both male and female bodies. Studies show that increased estrogen levels in males can reduce sex drive and decrease sperm concentration and motility

If you have high estrogen levels, you may experience loss of energy, hair loss, shrinking muscle mass, and trouble focusing. Since these symptoms can also be associated with the natural process of aging, it can be difficult to pinpoint this hormonal imbalance.


Prolactin is the hormone best known for stimulating breast milk production. However, it also plays several important roles in testicular function and semen production.

An overabundance of prolactin is known as hyperprolactinemia. According to research, this condition is seen in 11% of infertile males, and has been linked to reduced semen quality. High levels of prolactin can inhibit the production of gonadotropin-releasing hormone in the hypothalamus, a ripple effect that causes a decrease in FSH, LH, and testosterone—which, as we know, are key to healthy sperm production.

Thyroid-stimulating hormone

Thyroid-stimulating hormone (TSH), also produced in the pituitary gland, does basically what it says it does—it prompts the thyroid to spring into action, producing additional thyroid hormones that help maintain the body’s metabolic rate, heart and digestive functions, muscle control, brain development, and bone strength.

As in the case of FSH and LH, if your thyroid is not functioning properly, the pituitary will continue to produce a high level of TSH. Therefore, too-high or too-low levels of TSH in the blood can indicate a problem with the thyroid such as hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid).

Research shows that hypothyroidism has an adverse effect on male fertility, as it negatively impacts sperm parameters like count, morphology, and motility. Although studies have found that hypothyroidism has a negative impact on fertility, it is very rare in males, and affects less than 1% of the general male population.

Recognizing a imbalance in male fertility hormones

Since the symptoms of hormonal imbalance can look similar to the natural effects of aging, it's not always easy to catch. Symptoms of a male fertility hormone imbalance might include:

Testing male fertility

If you have been struggling to conceive or suspect that hormones may be the cause for infertility, there are a few male fertility testing options to consider.

A good starting point is a sperm analysis test. The test results will drill down on sperm quality parameters like count/concentration, motility, and morphology. This frontline test can help you understand if there may be an underlying factor that's impacting your fertility.

Nowadays, a sperm analysis can be done in the comfort of your own home. With Legacy's at-home sperm analysis kit, you can send in your sample and receive a confidential,  easy-to-understand report of your results, personalized recommendations, and guidance from the experts—all while maintaining your privacy and without having to leave home.

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