• An estimated 15% of couples experience infertility at some point and sometimes, there is no explanation for infertility.
  • Frequent bicycle riding, poor diet, testosterone and prostate cancer medications, as well as certain medical conditions can affect fertility in men.
  • Medical conditions such as PCOS, diabetes, cystic fibrosis, or autoimmune disorders are all associated with infertility in women.
  • Couples unable to conceive on their own after a year of trying should seek help from a fertility specialist.

Infertility is a condition that affects an estimated 15% of couples worldwide. Here’s what you need to know about how common infertility is, who it affects, and what factors can play a role. 

Factors that can cause infertility and men and women

According to the Centers for Disease Control and Prevention (CDC), in 35% of infertility cases, it’s related to a combination of factors in both the man and woman. 

And in some cases, the exact cause is not known. “Sometimes, there is no explanation,” says Maryanne George, a certified nurse-midwife with Spectrum Health.

What is known, however, is that there are certain medical conditions that can contribute to infertility in both men and women, such as: 

  • Hormonal disorders and pituitary, adrenal, and hypothalamus dysfunction.
  • Medical conditions such as diabetes, cystic fibrosis, and autoimmune disorders.
  • Pelvic infection
  • Cancer treatments like chemotherapy and radiation 

Additional factors that can cause infertility in men

Researchers estimate that about 40% to 50% of the time, the root factor is a cause of infertility in the male, alone. 

Where “male factors are often related to varicoceles or trauma that affects sperm production in the testes,” says George. 

For men, the key factors in determining fertility are both the quality and quantity of your sperm. High-quality sperm is often associated with high motility, which is a sperm’s ability to swim through the vagina, up the cervix, and into the fallopian tubes where it can fertilize an egg. If you have weak sperm, you’re less likely to impregnate a woman. Quantity — or how many sperm are in each ejaculation — is also important. The more the better.

There are many different ways to damage the quality and quantity of your sperm, George says. For example, activities and habits that expose your testicles to pressure or heat including:

  • Frequent bicycle riding
  • Supporting your computer on your lap
  • Wearing tight clothing in the groin area
  • Frequent time spent in jacuzzis or saunas

Then, there’s your diet and overall mental and physical health. Research has shown that many factors associated with an unhealthy lifestyle are also linked to infertility in men, including:

  • A poor diet low in fruits, vegetables, and other fiber-rich foods and high in processed meats, trans fats, and high-fat dairy
  • Drinking alcohol
  • Smoking — cigarettes or otherwise
  • Using anabolic steroids that promote muscle growth
  • Obesity and poor fitness
  • Chronic psychological stress
  • Insufficient sleep
  • Jet lag, working night shifts, or other disruptions to your circadian rhythm
  • Depression

Medications can also inhibit male infertility. According to the CDC, below are some examples of such medications. 

  • Prostate cancer medications 
  • Testosterone 
  • Spironolactone, a blood pressure medication 
  • Anti-fungal medicine like ketoconazole 
  • Cimetidine, which is used to treat heartburn and stomach ulcers
  • For the complete list of medications, visit the CDC.

There are also certain medical conditions that affect male infertility including:

  • Varicoceles, which is when the vein in your scrotum is larger than normal, which can reduce sperm quantity.
  • Infections or tumors of the reproductive organs such as epididymitis, which occurs when the tube that carries your sperm becomes inflamed.
  • Cryptorchidism is when your testicles don’t fully descend, which can affect sperm production
  • Hormonal imbalances such as low luteinizing and follicle-stimulating hormones, which are key in your production of testosterone and sperm
  • Celiac disease
  • Chromosome defects, which can cause a chemical pregnancy and lead to miscarriage.

Lastly, some research suggests that certain environmental chemicals — like BPA and phthalates — and pollution — like the air pollutants sulfur dioxide and carbon monoxide — can cause infertility in both men and women. Though, more research is needed to understand exactly how these factors play a role in overall reproductive health.