What Causes Infertility? It’s Complicated!

For many of us, our reproductive years go something like this…birth control, birth control, birth control, baby, birth control, birth control. We spend the vast majority of our reproductive years actively trying to prevent pregnancy, desperately avoiding any minor slip-up that may lead to a wayward sperm and a determined egg meeting at a time when we aren’t ready.  

The seeming simplicity of it all adds to the heartbreak and shock that we feel when, after years of trying NOT to get pregnant, we find ourselves trying to conceive without success.  

The truth is, human reproduction is wildly complex. There are thousands of steps that have to go right in order for a pregnancy to occur and millions more that are required for a healthy baby to be born. If any of these steps go awry, the system breaks down and the result is another month with a negative pregnancy test.

Despite our perceptions about the ease at which others are able to conceive, the statistics on “normal” reproductive success are quite eye-opening. The chance that a female in her 30’s will conceive each month is only about 20%, a number that drops to 5% by the time that same individual is 40 years old.  Pair this with the fact that 10-20% of all pregnancies end in miscarriage, and it is truly a wonder that any of us exist at all.  

Primary & Secondary Infertility

Infertility is described as either “primary” or “secondary.” Primary infertility refers to infertility in an individual or couple who have never achieved a pregnancy before. Secondary infertility is present in those who have previously had a successful pregnancy and are now unable to conceive.  

The causes of infertility are equally attributed across all genders as well as unknown causes. Taking some time to become familiar with some of the most common causes of infertility can help you to feel less overwhelmed as you work to find the source of your own fertility struggles.  

Investigating Infertility

In the past 50 years, science has made incredible advancements in our understanding of the process of reproduction. These insights have enabled us to develop diagnostic and treatment strategies that can improve the chance of a successful pregnancy for many individuals and couples who would have been unable to conceive on their own. With infertility affecting approximately 48 million couples and 186 million individuals globally, the continued investigations into the causes and treatments for infertility are critical (World Health Organization, “Infertility” Fact Sheet, Sep 14, 2020).

causes of infertility can be grouped into primary or secondary infertility

As you can imagine, there are as many causes of infertility as there are things that can go wrong during the timeline between conception to birth. Due to this fact, the path to identifying the cause of infertility can be frustrating and long. In some cases, treatment with advanced reproductive technologies is required before a cause is identified. In other cases, the underlying cause of infertility is never determined. 

The evaluation to find the cause of infertility is designed to identify factors that may contribute to an individual’s or couple’s difficulty achieving a pregnancy. The assessment begins by evaluating the two broad systems involved in reproduction – anatomy and hormones. More focused and detailed testing is then performed for each abnormality that is identified until a final diagnosis is made.  

Causes of Infertility


Causes of infertility could be related to sperm motility and mobility

Abnormalities in sperm are found in a number of individuals who suffer from infertility. A semen analysis can help to identify such abnormalities and assess changes in the sperm parameters over time. Conditions resulting in low sperm number, poor sperm motility (the ability of the sperm to move), or a high number of abnormally shaped sperm (abnormal morphology) can all significantly impact pregnancy rates.

Knowing which components of the semen analysis are abnormal allows for the selection of a treatment plan that will result in the highest chance of fertilization.

The evaluation of the reproductive system relating to the ovaries and uterus is more involved as, anatomically, there are more factors to be considered. The cause of infertility for these individuals can be a range of abnormalities of the ovaries, uterus, fallopian tubes, and the hormonal system, among others.  


The most common cause of infertility is ovulatory dysfunction. In this condition, the ovary does not reliably grow and release an egg each month. While there are a number of causes of ovulatory dysfunction (such as a low or high BMI, premature ovarian failure, advanced maternal age, and more) the most frequent cause by far is Polycystic Ovarian Syndrome, otherwise knowns as PCOS 

Polycystic Ovarian Syndrome (PCOS)

PCOS is a common hormonal disorder that predominantly affects individuals during their reproductive years. Those with PCOS can experience infrequent or prolonged menstrual periods and it often interferes with the growth and release of eggs. They may also have signs of higher than normal male hormones (androgen) levels, such as unwanted hair growth on the face or abdomen. Once a diagnosis of PCOS is confirmed, treatment with fertility medications can often result in the return of predictable ovulatory cycles. 

Diminished Ovarian Reserve (DOR)

On the other end of the ovulatory dysfunction spectrum is a condition known as Diminished Ovarian Reserve (DOR).  In this condition, the egg supply is low, which decreases the chance of pregnancy each month. As women are born with all of the eggs they are ever going to have, the diagnosis of DOR increases as a woman ages. Although DOR may make it more challenging to conceive, success is still possible in many cases with fertility treatments such as In Vitro Fertilization (IVF).

Fallopian Tubes

Tubal Factor Infertility

Tubal factor infertility, in which one or both of the fallopian tubes are blocked or structurally abnormal, is next on this list of the most common causes of infertility.  Although they appear to be simple tubes that act as conduits for eggs and sperm, the fallopian tubes are actually extremely delicate and functional structures.  

They are lined with hair-like structures, called cilia, and are responsible not only for catching the egg after ovulation but making sure the egg and sperm meet, as fertilization actually happens in the tube! The resultant embryo travels back to the uterus where it can implant and grow.  

Damage or blockage to the fallopian tube can be caused by a number of things including pelvic inflammatory disease, previous surgery, pelvic tuberculosis, chlamydia, and more. 

Most of the time, abnormalities of the tube are completely asymptomatic.  This means that those individuals who have blocked or damaged tubes aren’t even aware this could be contributing to their inability to conceive. Evaluating the fallopian tubes is a crucial part of the fertility evaluation and if a tubal disease is identified, it can significantly.



Uterine and cervical abnormalities can have a big impact on one’s ability to conceive. Polyps or fibroids (benign tumors), scarring, inflammation, or an abnormally shaped uterus or cervix can affect the ability of the sperm to meet the egg and successful implantation. 

woman gardening with endometriosis which could create trouble getting pregnant


A discussion of causes of infertility would not be complete without a mention of endometriosis.  Endometriosis is a condition in which the interior lining of the uterus implants in places outside of the uterine cavity, such as the surface of the uterus, bowel, bladder, and/or ovaries.  

Classically, endometriosis causes painful periods, but this is not always the case.  Endometriosis can be tricky, with some individuals having no symptoms at all.  The diagnosis of endometriosis is most often a clinical one, meaning the physician evaluates for the signs and symptoms of endometriosis, and if they are present, the physician will diagnose it. 

As endometriosis is thought to be the cause of infertility in about 15% of cases, it is certainly one of the causes your provider will be looking for evidence of during an evaluation. 

Hormonal Abnormalities

Hormones are a delicate and tricky balance. Take one piece of the puzzle away and the reproductive system can have trouble functioning in the correct way. There are many hormonal abnormalities, including hypothyroidism, hyperprolactinemia, hypothalamic dysfunction, and many more.

Even these less common causes of infertility are evaluated for the typical infertility assessment to ensure that all of the potential contributing factors are addressed when a treatment plan is created for you.  

Additional Causes of Infertility

Sexual Function

Issues with sexual function can affect all partners in the relationship. Sexual dysfunction or pain can make having intercourse difficult and painful. 

The inability to get or maintain an erection, known as ejaculatory dysfunction, as well as the inability to ejaculate, are both conditions that prevent the delivery of sperm.  Even in the setting of normal sperm parameters, such conditions can drastically decrease the chances of getting pregnant. 

Treatments are available that can improve sexual function and help a couple to achieve a pregnancy through intrauterine insemination (IUI). 

Social Infertility

a cause of infertility can be socially or due to a person's circumstances and relationships.

Many intended parents need help growing their family due to reasons beyond a physical diagnosis. Social infertility is due to a person’s circumstances and relationships. For example, due to the absence of sperm for a same-sex female couple, they would need to bring in a sperm donor to grow their family. Sperm donors, egg donors, and surrogates (gestational carriers) can not only help those with clinically diagnosed infertility but can also help LGBTQ+ families grow as well, along.


Location can also play a major role in the ability for intended parents to grow their families, whether you are infertile due to physiological reasons or need assistance due to social infertility, you still need access to care. Those living in rural areas or countries that might lack infertility care that’s available have trouble even getting the process started. 

Even more of a barrier in some parts of the world are legal restrictions making it difficult to access fertility treatment. In the past, there have been laws making the buying and selling donor sperm or eggs illegal, IVF for single women, men or LGBTQ+ illegal, strict laws around surrogacy, and more. 

While lobbying continues and we see access to fertility care increasing in many countries, there are still a number of areas around the globe where it is nearly impossible to seek fertility care for certain couples and individuals.  

Unexplained Infertility

Lastly, and probably the most frustrating of all, is the reality that sometimes we can’t find an explanation.

It’s Complicated!

So simply put, fertility is complicated. And because there are so many places in which the process can get off-track or barrier, infertility might be more common than you think. And with the increase in telehealth opportunities, access to fertility care is becoming more common in places it previously wasn’t. For many, the journey to parenthood does not go as planned. 

Infertility is complicated and sometimes the cause someone is having trouble getting pregnant is left unknown

Sometimes it truly does take a village. The good news is, success can often be found with the help and support of a care team and community that understands where you are at and can help you navigate the journey. And the first step is finding your village.         

If you are facing trouble conceiving or want to learn more about your options for fertility care at ORM Fertility by scheduling a consultation with one of our fertility specialist!


Infertility Could Be Related To…

An exhausting, but not an exhaustive list, of the potential causes of infertility can help us understand the complexity of this process and hopefully serve as a reminder that you are not alone! There are many individuals who need a little help building the family of their dreams and identifying the barriers to building that family is the first step of the journey.

  • Ovaries 
    • Ovulatory dysfunction
      • Too low or high BMI 
      • Stress 
      • Premature ovarian failure
      • Thyroid dysfunction
    • Irregular cycles/ovulation
    • Polycystic Ovarian Syndrome (PCOS) 
    • Thyroid Dysfunction 
    • Hyperprolactinemia 
    • Hypothalamic dysfunction
  • Diminished Ovarian Reserve (DOR) (Egg quantity & quality decreases over time) (Advanced Maternal Age)
  • Fallopian Tube
    • Fallopian Tube Blockage
      • Proximal blockage 
      • Distal blockage 
      • Hydrosalpinx blockage
    • Abnormal Fallopian Tube Shape
    • Fallopian Tube Damage
      • Pelvic Inflammatory Disease 
      • Ruptured Appendix 
      • Pelvic Surgery/Adhesions
      • Ectopic Pregnancy 
      • Tubal Ligation 
      • Endometriosis
  • Uterus
    • Congenital Uterine Abnormalities 
    • Fibroids
    • Intrauterine Scarring 
    • Asherman’s Syndrome 
    • Polyps 
  • Cervical abnormalities
  • Endometriosis
  • Cancer & Cancer treatment
  • Hypothyroidism & Hyperprolactinemia
  • Sperm 
    • Low Concentration/Count
    • Poor Motility
    • Abnormal Morphology
    • Problems delivering sperm 
      • Difficulty maintaining an erection
      • Difficulty ejaculating/delivering sperm
  • Genetic & Chromosomal Abnormalities
  • Exposure to environmental factors 
    • Chemicals & radiation 
    • Cigarette smoking
    • Marijuana
    • Anabolic Steroids
  • Social Infertility
  • and many more

Work with an LGBTQ+ inclusive fertility clinic.