Other Causes of Infertility

Infertility can be complex and emotionally challenging. While conditions such as polycystic ovarian syndrome (PCOS), endometriosis, and uterine fibroids are common causes of fertility difficulties, many other factors may also affect the ability to conceive.

Understanding these additional causes helps couples feel informed and reassured that a thorough and structured approach is available. Fertility is influenced by both female and male factors, as well as lifestyle, medical history, and age. In many cases, identifying the underlying cause allows for targeted treatment and improved outcomes.

Ovulation Disorders (Non-PCOS Related)

Ovulation is essential for pregnancy. Even if menstrual cycles appear regular, ovulation may not always occur properly.

Common ovulation-related causes include:

• Hypothalamic dysfunction: Stress, excessive exercise, rapid weight loss, or being underweight can disrupt hormone signals from the brain.
• Hyperprolactinaemia: High prolactin levels (sometimes due to a benign pituitary gland condition) can prevent ovulation.
• Thyroid disorders: Both underactive and overactive thyroid conditions can interfere with menstrual cycles and fertility.
• Premature ovarian insufficiency (POI): When the ovaries stop functioning normally before age 40.

These conditions are often identified through blood tests and can frequently be managed with medication or lifestyle adjustments.

Age-Related Fertility Decline

Female fertility naturally declines with age, particularly after 35 years. This decline is related to:

• Reduced egg number: Women are born with a finite number of eggs.
• Reduced egg quality: The likelihood of chromosomal abnormalities increases with age.
• Higher miscarriage risk: Miscarriage rates rise as egg quality declines.

Male fertility also gradually declines with age, affecting sperm quality and increasing the risk of genetic changes.

Early fertility assessment can help individuals understand their reproductive timeline and options, including egg freezing where appropriate.

Tubal Factors

The fallopian tubes play a vital role in fertilisation. Damage or blockage can prevent the sperm and egg from meeting.

Common causes of tubal damage include:

• Previous pelvic infections
• Sexually transmitted infections (STIs)
• Prior abdominal or pelvic surgery
• Appendicitis complications
• Pelvic inflammatory disease (PID)

Testing often involves imaging, such as a hysterosalpingogram (HSG) or specialised ultrasound. If tubes are blocked, treatment options may include surgery or in vitro fertilisation (IVF).

Adenomyosis

Adenomyosis is a condition where tissue similar to the lining of the uterus grows into the muscular wall of the uterus, which can lead to heavy periods, pelvic pain, and sometimes difficulty conceiving due to changes in the structure and function of the uterus.

The exact cause of adenomyosis is not fully understood, but several factors are believed to contribute to its development.

• Hormonal influences: Oestrogen may stimulate the growth of endometrial tissue within the uterine muscle.
• Previous uterine surgery: Procedures such as caesarean section or curettage may disrupt the boundary between the uterine lining and muscle.
• Childbirth: Multiple pregnancies may weaken the uterine wall and contribute to tissue growth into the muscle.
• Age and reproductive history: Adenomyosis is more common in women aged 30–50, particularly those who have had children.
• Uterine inflammation: Chronic inflammation after pregnancy or infection may allow endometrial tissue to penetrate the uterine muscle.

Male Factor Infertility

Male factors contribute to infertility in approximately 40–50% of cases. A semen analysis is a simple but essential test.

Common male causes include:

• Low sperm count
• Poor sperm motility (movement)
• Abnormal sperm shape
• Hormonal imbalance
• Varicocele (enlarged veins in the scrotum)
• Genetic conditions

Lifestyle factors such as smoking, obesity, anabolic steroid use, and excessive heat exposure can also affect sperm quality.

Early testing ensures both partners are assessed simultaneously, avoiding delays.

Genetic Factors

Some couples may carry genetic variations that affect fertility, embryo development, or increase miscarriage risk.

Examples include:

• Balanced chromosomal translocations
• Y-chromosome microdeletions (in men)
• Single gene disorders

Genetic carrier screening and karyotype testing may be recommended in cases of recurrent miscarriage or severe male infertility.

Advances in reproductive genetics allow for pre-implantation genetic testing (PGT) in selected IVF cases.

Autoimmune and Immune-Related Conditions

Certain immune disorders may affect implantation or pregnancy progression.

Examples include:

• Antiphospholipid syndrome
• Lupus
• Autoimmune thyroid disease

These conditions may increase miscarriage risk but can often be managed successfully once identified.

Uterine Structural Abnormalities (Non-Fibroid Related)

Aside from fibroids, structural issues may interfere with implantation.

These include:

• Congenital uterine abnormalities (septate uterus, bicornuate uterus)
• Intrauterine adhesions (Asherman’s syndrome)
• Endometrial polyps

Imaging tests such as pelvic ultrasound, saline sonography, or hysteroscopy help diagnose these issues.

Many structural conditions can be corrected surgically.

Unexplained Infertility

In some couples, all investigations return normal results. This is called unexplained infertility.

It does not mean there is no cause. Rather, it suggests that:

• Current testing cannot identify the issue
• Subtle egg, sperm, or implantation factors may be involved

Treatment options may include:

• Ovulation induction
• Intrauterine insemination (IUI)
• IVF

Success rates remain good with guided treatment.

Lifestyle and Environmental Factors

Modern lifestyle factors can significantly affect fertility in both men and women.

Contributing factors include:

• Smoking
• Excess alcohol consumption
• Obesity
• Underweight BMI
• High stress levels
• Poor sleep
• Exposure to environmental toxins

Optimising general health improves both natural conception and assisted reproduction outcomes.

Chronic Medical Conditions

Long-term health issues may interfere with fertility.

Examples include:

• Diabetes
• Coeliac disease
• Chronic kidney disease
• Severe asthma
• Cancer treatments (chemotherapy or radiation)

Pre-conception planning is particularly important for individuals with chronic medical conditions to ensure safe pregnancy management.

Sexual Function Difficulties

Fertility may be affected by physical or psychological factors that interfere with intercourse timing.

Examples include:

• Erectile dysfunction
• Painful intercourse
• Low libido
• Performance anxiety

Addressing these concerns early can significantly improve the chances of natural conception.

How Are These Causes Investigated?

A structured fertility assessment may include:

• Detailed medical history
• Hormone blood tests
• Semen analysis
• Pelvic ultrasound
• Tubal testing
• Genetic testing where appropriate

Individualised testing avoids unnecessary procedures while ensuring important causes are not missed.

Infertility Treatment Options

Management depends entirely on the identified cause. Treatment may involve:

• Lifestyle optimisation
• Medication to stimulate ovulation
• Hormone correction
• Surgical procedures
• Assisted reproductive techniques such as IUI or IVF
• Genetic counselling

A personalised approach offers the best chance of success.

When to Seek Help?

It is recommended to seek a fertility assessment if:

• You are under 35 and have tried for 12 months without success
• You are over 35 and have tried for 6 months
• You have irregular periods
• You have a history of pelvic infection or surgery
• You have had recurrent miscarriages
• You have known medical conditions affecting fertility

Earlier assessment may reduce emotional stress and shorten the time to diagnosis.

Prognosis and Outlook

Many causes of infertility are treatable. Advances in reproductive medicine have significantly improved success rates over the past decades.

Even when natural conception is not possible, assisted reproductive technologies offer effective alternatives.

The most important step is a thorough and supportive evaluation.