The Most Common Causes of Infertility & How They’re Treated

Infertility can feel incredibly personal, but it's not a personal failure. Defined as the inability to conceive after 12 months of regular, unprotected sex (or 6 months for women over 35), infertility affects millions of individuals and couples worldwide. It's far more common than most people realize, and more treatable, too.

Understanding the root causes of infertility is the first step in finding the right treatment. Whether the issue lies with the female reproductive system or the male, modern medicine offers a wide range of solutions. In many cases, a proper diagnosis brings not just clarity but hope.

This article will look at the most common causes of infertility and what you can do about them.

Female Fertility Issues

Women’s reproductive systems are complex in many ways and sensitive to a variety of factors. From hormone levels to age, anatomical issues, and underlying medical conditions, different factors can cause infertility. 

PCOS and Infertility

Polycystic Ovary Syndrome (PCOS) is one of the most common causes of female infertility. It affects how the ovaries work, often preventing regular ovulation. PCOS symptoms are:

• Irregular or absent menstrual cycles
• Elevated androgen (male hormone) levels
• Multiple small follicles or “cysts” on the ovaries
• Insulin resistance

Without regular ovulation, there’s no egg to fertilize, making conception difficult. PCOS can also impact egg quality and increase the risk of miscarriage. Treatment options can include:

• Lifestyle changes such as weight loss, a low-carb diet
• Ovulation-inducing medications like Clomid
• Metformin for insulin resistance
• IVF for resistant cases

Endometriosis and Its Impact on Conception

Endometriosis is a condition where the tissue that normally lines the uterus grows outside the uterus, often on the ovaries, fallopian tubes, or pelvic lining. Endometriosis does affect fertility in different ways:

• Scar tissue may block or damage the fallopian tubes
• Chronic inflammation can interfere with egg quality
• Implantation may be disrupted

Treatment options for endometriosis include:

• Laparoscopic surgery to remove lesions
• Hormonal therapy to reduce growths
• IVF to bypass structural issues

Endometriosis often goes underdiagnosed, so if you have painful periods, pain during sex, or digestive issues, bring it up with your doctor.

Low Ovarian Reserve and Age-Related Decline

As women age, the number and quality of their eggs naturally decrease. This decline becomes more noticeable after age 35 and more pronounced after 40. This can negatively impact fertility because fewer eggs are available for ovulation,  and there’s an increased risk of chromosomal abnormalities. 

Signs of low ovarian reserve are:

• Irregular periods
• Low Anti-Müllerian Hormone (AMH) levels
• High Follicle-Stimulating Hormone (FSH) levels

Treatment options for low ovarian reserve include:

• IVF with ovarian stimulation
• Egg or embryo freezing (mostly for younger women)
• Donor eggs for women with very low reserve
• Supplements like DHEA or CoQ10 (under medical guidance)

Male Fertility Issues

Men contribute to a large percentage of all infertility cases. The focus is often on sperm count, motility (movement), morphology (shape), and overall sperm health.

Low Sperm Count and Poor Motility

A healthy sperm count is essential for fertilization, but numbers aren’t everything. Sperm need to be mobile, well-formed, and present in high enough concentrations to reach and penetrate the egg. Common causes are:

• Hormonal imbalances
• Varicoceles (vein swelling in the scrotum)
• Lifestyle factors like smoking, obesity, and drug use
• Exposure to heat or toxins

To treat low sperm count and poor motility, fertility doctors recommend:

• Lifestyle improvements such as diet, exercise, and reducing heat/exposure
• Hormone therapy
• Supplements like zinc, vitamin C, and CoQ10
• IUI or IVF with ICSI (injecting sperm directly into the egg)

Varicocele and Its Impact on Sperm Health

A varicocele is an enlargement of the veins within the scrotum. It’s similar to a varicose vein, and one of the most common causes of low sperm quality. Symptoms of varicoceles include:

• Dull testicular pain
• A feeling of heaviness or swelling
• Noticeable veins, especially when standing

Varicoceles increase testicular temperature, which can impair sperm production and function. To treat them,  a doctor may propose:

• Surgical repair, called a varicocelectomy
• Assisted reproductive technologies like ICSI
• Ongoing monitoring and semen analysis

Unexplained Infertility: What It Means

Sometimes, even after thorough testing, no specific cause of infertility can be found. This is known as unexplained infertility, and it accounts for 10–20% of cases. Possible contributing factors can be:

• Subtle hormonal imbalances
• Egg or sperm quality issues not detected by standard tests
• Immune or inflammatory responses
• Endometrial receptivity problems

To treat unexplained infertility, your fertility clinic may first ask you to make lifestyle changes such as diet, stress management, and more sleep. You may also be given ovulation-stimulating medications even if your cycle is regular. If those don’t work, Intrauterine insemination (IUI) or in vitro fertilization (IVF) may be the next step.

Unexplained infertility can be frustrating, but it doesn’t mean treatment won’t work. It just means the cause isn’t obvious yet.

Fertility Treatment Options for Every Condition

Thankfully, infertility is often treatable, but the right treatment depends on your diagnosis, age, health, and personal goals. Common treatment options include:

• Lifestyle changes.
• Fertility medications
• Intrauterine insemination (IUI)
• In vitro fertilization (IVF)
• Intracytoplasmic sperm injection (ICSI)
• Use of donor eggs, sperm, or embryos
• Gestational surrogacy

Treatment plans are personalized and may involve a combination of these methods.

FAQs

What are the top causes of female infertility?

The top causes of infertility include:

• Ovulatory disorders (e.g., PCOS)
• Irregular or absent ovulation
• Fewer, lower-quality eggs after age 35
• Endometriosis
• Fallopian tube damage
• Fibroids or polyps that interfere with implantation
• Hormonal imbalances 

What is unexplained infertility?

Unexplained infertility is infertility without a known cause. It’s diagnosed when all standard fertility tests are normal, but pregnancy still doesn’t happen. It may involve:

• Subtle egg or sperm issues
• Implantation problems
• Minor hormonal fluctuations
• Immune system dysfunction

Can infertility be cured?

Absolutely! But the treatment option depends on the cause. Hormonal issues and ovulation disorders are often treatable with medications. Tubal blockages or severe endometriosis may require IVF, while low ovarian reserve or age-related infertility, though can’t be reversed, might be dealt with using donor eggs. Male infertility may be managed with ICSI, surgery, or sperm retrieval.  While not all causes can be cured, many can be managed effectively to achieve pregnancy.

How do I know if I need IVF?

You might need IVF if:

• You have blocked or missing fallopian tubes
• Male factor infertility is severe
• You’ve tried IUI multiple times without success
• You have low AMH or high FSH
• You don’t respond to fertility medications
• You have unexplained infertility
• You need genetic screening (PGT)

A fertility specialist will guide you based on test results and your reproductive history.

What are my options if I have low ovarian reserve?

Low reserve doesn’t mean no chances of conception. Timing is critical, and the sooner you act, the better. There are still different options available, including:

• IVF with aggressive stimulation protocols
• Donor eggs (higher success rates)
• DHEA or CoQ10 supplementation (under supervision)
• Embryo banking across multiple cycles
• Early fertility preservation (egg freezing if not ready to conceive yet)

Conclusion

Infertility can feel isolating, but you’re far from alone. Whether the cause is clear or remains unexplained, today’s fertility treatments offer more hope than ever. From lifestyle changes and simple medications to advanced technologies like IVF and ICSI, there are paths forward for nearly every situation.