If you're on a fertility journey, understanding the root causes of infertility is a crucial step in moving forward. Whether it's male factor, female factor, or a combination of both, many of the underlying causes of treatable and once treated improve chances of a healthy pregnancy and baby!. 


Incidence: A 30-30-30 Split

When discussing causes of infertility, it’s important to know that the causes are divided relatively evenly between male and female factor (I know 3, 3rd doesn't make a whole...). About 30% of infertility cases are due to male factors, 30% are due to female factors, and 30% are combined and ~10% unexplained. This highlights the importance of investigating both partners during fertility evaluations, and not automatically taking on the brunt of responsibility as the female partner. 


Male Factor Infertility: Focus on Sperm Quality and Quantity

Male factor infertility is typically diagnosed with a semen analysis, which looks at key sperm parameters like count, motility (movement), and morphology (shape). Here are some common causes of altered semen parameters: 


  • Hormonal Imbalances: Reproductive hormones, primarily testosterone, are essential for sperm production. Elevated levels of estrogen or prolactin can negatively impact sperm quality. This includes previous or current use of anabolic steroids. 

  • Structural Issues: Including conditions like varicocele, which is essentially a varicose vein in the testicles, or cryptorchidism, also known as undescended testis. 

  • Injury to Testes; physical, radiation or infectious (think STIs/STDs)

  • Sexual Dysfunction: Conditions like erectile dysfunction or ejaculation issues impair the ability to conceive. 

  • Congenital or Genetic Issues: Kleinfelter Syndrome and Cystic Fibrosis influence male gonadal function and spermatogenesis

  • Metabolic health; obesity and diabetes are known to alter sperm production and androgen (including testosterone) production 

  •  Sperm DNA Fragmentation: This is when the DNA within sperm is damaged, leading to prolonged conception times or recurrent pregnancy loss. An advanced semen analysis can identify this issue.


Many of the underlying causes of male factor infertility are treatable, thereby improving semen parameters and improving chances of conception! 


Female Factor Infertility: Ovarian, Tubal, and Uterine Health

Female infertility is a bit more complex, as it involves various systems within the reproductive tract. Let’s break down the three major categories: ovarian, tubal, and uterine causes.


Ovarian Issues: The Most Common Cause

The biggest contributor to female infertility is ovarian dysfunction, which can include:

  • Age-related Infertility: As women age, the number and quality of eggs decline, reducing the chances of conception.

  • Polycystic Ovarian Syndrome (PCOS): This hormonal disorder affects ovulation and is a leading cause of infertility.

  • Premature Ovarian Insufficiency (POI): This is when the ovaries stop functioning normally before the age of 40, leading to a decreased egg reserve.

  • Anovulation: This is the absence of ovulation, which can be caused by conditions like hypothalamic amenorrhea or thyroid disorders.


Tubal Issues: Can the Egg and Sperm Meet?

Tubal issues occur when the fallopian tubes, which transport eggs from the ovaries to the uterus, are blocked or damaged. Common causes include:

  • Ectopic Pregnancy: This can cause damage or potential loss of the fallopian tube, reducing fertility.

  • Infections: STIs or pelvic inflammatory disease (PID) can cause scarring or blockages.


Uterine Issues: The Environment for Implantation

Uterine abnormalities/growths or alterations can also interfere with fertility. This is the environment that needs to host the embryo and fetus over the next 9 months, a healthy uterine environment is key for fertility and ongoing pregnancy! Key issues include:

  • Endometriosis: A condition where tissue similar to the lining of the uterus grows outside the uterus, leading to scarring and fertility issues.

  • Fibroids or Polyps: Non-cancerous growths in the uterus that may prevent implantation.

  • Lining Issues: The uterine lining may be too thin or irregular, preventing the successful implantation of an embryo.

  • Microbiome Dysfunction: A lactobacillus-dominant uterine microbiome is required for implantation and ongoing pregnancy. Low lactobacillus species and/or infectious bacterial species can alter fertility.


While about 30% of infertility cases are female facto exclusively, remember an additional 30% is made up of combined male and female factor. The additional percentage, "unexplained".


Unexplained Infertility: The Deeper Dive

Unexplained infertility is where neither partner appears to have obvious issues. This is where more in-depth investigations come in and where naturopathic medicine shines. Here are a few things to consider:


Metabolic Health

Conditions like insulin resistance can delay conception and increase the risk of miscarriage. Insulin resistance is also linked to conditions like PCOS, and addressing it is key to improving fertility outcomes.


Nutrient Deficiencies

Key nutrients, especially vitamin D and iron, play critical roles in fertility. Low levels of vitamin D (under 110 nmol/L) can increase the risk of pregnancy loss. Many women with histories of miscarriage often have low levels of these essential nutrients, and addressing deficiencies can make a significant difference.


Autoimmunity

Sometimes, the immune system can interfere with fertility. Conditions like Hashimoto’s thyroiditis or celiac disease can affect reproductive health. Even subtle immune imbalances, like heightened responses to infections or toxins, can disrupt implantation.


Lifestyle Factors

Endocrine-disrupting chemicals, caffeine, alcohol, and marijuana use can all impact egg and sperm quality. Cutting back or eliminating these can improve fertility outcomes.  


Unexplained infertility isn't an end diagnosis, it's an open door indicating there's more to explore. Many factors can still be investigated and optimized to improve your chances of getting—and staying—pregnant.


Conclusion: Stay Hopeful!

Infertility often feels like a dead end, but understanding its causes can help guide your next steps. Whether it's male or female factor, or a combination of both, there are always strategies to improve your reproductive health. By digging deeper into metabolic and lifestyle factors, even unexplained infertility can often be explained—and treated. Stay hopeful, take it step by step, and don’t hesitate to reach out to your healthcare provider for personalized support on your journey!

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About the Author

Dr. Liza Klassen, ND

A fertility-focused ND who bridges the medical and emotional aspects of fertility, recognizing that the journey to conception is not solely clinical but also deeply personal. She is passionate about helping her patients achieve and maintain healthy pregnancies whether natural or assisted and works collaboratively with reproductive endocrinologists and ART team to deliver high-quality & efficacious care.