Causes of Infertility in Men and Women

Overview

Infertility is a reproductive health concern that affects millions of couples and individuals worldwide. Although it is often associated with women, fertility depends on both partners. The causes of infertility may involve factors affecting the woman, the man, or both. In some cases, the exact cause remains unexplained, even after a detailed medical evaluation.

Many causes of infertility can be identified through appropriate medical examinations, and some may be managed with suitable treatment. Advances in reproductive medicine have also created more options for individuals and couples experiencing difficulty conceiving. Understanding potential risk factors and seeking medical advice at the right time can help people make informed decisions about their reproductive health.

This article explores the main causes of infertility in men and women, along with common risk factors, possible signs, diagnostic methods, and practical ways to support reproductive health. Whether you are planning to start a family now or considering pregnancy in the future, understanding these factors can help you take informed steps on your fertility journey.

Before exploring the causes in detail, here are a few important points to remember:

Healthy habits support reproductive health: Balanced nutrition, healthy lifestyle choices, and regular medical check-ups can contribute to overall well-being..

Infertility can affect both men and women: The underlying cause may involve one partner or both partners.

Several factors can influence fertility: Age, medical conditions, hormonal changes, and lifestyle habits may all play a role.

Early evaluation can be helpful: Appropriate medical guidance may identify treatable conditions and help determine suitable options.

What is Infertility?

Infertility generally means not becoming pregnant despite having regular, unprotected sexual intercourse for a certain period.

Healthcare professionals generally use the following timeframes when deciding when an infertility examination may be appropriate:

It is important to remember that infertility does not automatically mean pregnancy is impossible or that the condition will always be permanent. Some causes may be temporary or treatable, while others may require medical treatment or assisted reproductive techniques. A timely evaluation can help identify the possible cause and clarify what to do next.

Infertility Is a Shared Concern

A common misconception is that infertility is mainly a women’s problem. In reality, conception depends on the reproductive health of both partners.

In general:

The exact percentages can differ between studies and populations, but they make one point clear: male related factors are an important part of infertility and can be nearly as common as female related factors. For this reason, fertility assessment often involves both partners rather than placing the focus on only one person.

How Does Pregnancy Normally Occur?

Understanding how pregnancy normally begins can help explain where fertility problems may occur.

For pregnancy to happen naturally, several steps must work properly:

A healthy egg is released from the woman’s ovary during ovulation.

Healthy sperm are produced and are able to travel through the reproductive tract.

A sperm successfully fertilizes the egg inside the fallopian tube.

The fertilized egg, or embryo, moves through the fallopian tube toward the uterus.

The embryo attaches to the uterine lining and continues developing.

If any one of these steps is affected, getting pregnant may be harder.

The Fertility Journey: A Simple Flowchart

A problem anywhere along this pathway can potentially contribute to infertility. Issues with ovulation, sperm quality, blocked fallopian tubes or embryo implantation are some examples.

Types of Infertility

Infertility is generally divided into two main types.

Primary Infertility

Primary infertility refers to a couple who has never achieved a pregnancy despite having regular, unprotected intercourse for the recommended period of time.

Secondary Infertility

Secondary infertility occurs when a couple has achieved pregnancy at least once in the past but is now having difficulty becoming pregnant again.

Secondary infertility is more common than many people realise. It may be linked to factors such as increasing age, hormonal changes, medical conditions or complications that developed after an earlier pregnancy.

Why Does Infertility Occur?

Infertility is not one single disease. In most cases, it is related to one or more factors that affect the reproductive system.

Common involved factors:

• Hormonal imbalances
• Problems with ovulation
• Low or abnormal sperm production or function
• Blocked reproductive passages
• Age-related changes in fertility
• Lifestyle habits such as smoking and excessive alcohol consumption
• Obesity or being significantly underweight
• Certain long-term medical conditions
• Environmental exposures
• Genetic factors

Sometimes, even after a thorough medical evaluation, no specific cause can be identified. This is referred to as unexplained infertility.

Can Lifestyle Affect Fertility?

Yes. Although some causes of infertility are outside a person’s control, everyday lifestyle choices can have an important influence on reproductive health in both men and women.

Some habits and factors that may affect fertility include:

• Smoking tobacco
• Excessive alcohol consumption
• Poor nutrition
• Lack of physical activity

Obesity

• Long-term stress
• Not getting enough sleep
• Exposure to certain environmental toxins

By contrast, maintaining a healthy weight, eating a varied diet, staying physically active, managing stress and avoiding tobacco can support reproductive health and may help fertility in some people.

Common Signs That May Suggest Fertility Problems

Infertility does not always produce noticeable symptoms, particularly in men. Still, certain changes may suggest an underlying reproductive health problem.

Women may notice:

• Irregular menstrual cycles
• Very painful periods
• Periods that are absent
• Very heavy or unusually light bleeding
• Pelvic pain
• Difficulty identifying or predicting ovulation

Men may experience:

• Difficulty with ejaculation
• Reduced sexual desire
• Pain, swelling or discomfort in the testicles
• Changes in erectile function
• A previous history of undescended testicles or testicular injury

These signs do not necessarily mean that a person is infertile. However, if they continue or cause concern, discussing them with a healthcare professional is advisable.

What Causes Infertility in Women?

Female fertility relies on several parts of the reproductive system working together, including the ovaries, fallopian tubes, uterus and hormones. Problems involving any of these areas can make conception more difficult.

Some of the more common causes include:

• Ovulation disorders
• Polycystic Ovary Syndrome (PCOS)
• Endometriosis
• Blocked or damaged fallopian tubes
• Uterine fibroids or polyps
• Hormonal imbalances
• Age-related changes in egg quality
• Premature ovarian insufficiency
• Certain autoimmune or chronic medical conditions

The sections below explain these causes in more detail, including how they may affect fertility, possible symptoms and situations in which medical evaluation may be appropriate.

Common Causes of Female Infertility

Female fertility depends on a delicate interaction between hormones and the proper functioning of the ovaries, fallopian tubes, uterus and other parts of the reproductive system. If one part of this process is disrupted, natural conception may become more difficult.

It is worth remembering that infertility does not automatically mean pregnancy is impossible. Many underlying causes can be identified and managed with appropriate medical care, which is why timely evaluation can be helpful for individuals or couples experiencing difficulty conceiving.

Some of the common causes of female infertility are discussed below.

1. Ovulation Disorders

Ovulation is when a mature egg is released from the ovary, usually during the menstrual cycle. If ovulation happens irregularly or does not happen at all, the opportunity for fertilization can be greatly reduced.

Ovulation problems are one of the most common causes of female infertility.

Possible causes of ovulation disorders include:

• Polycystic Ovary Syndrome (PCOS)
• Thyroid disorders
• High prolactin levels
• Premature ovarian insufficiency
• Hormonal problems involving the pituitary gland or hypothalamus

Possible Signs and Symptoms:

• Irregular menstrual cycles
• Missed periods
• Very light or very heavy periods
• Difficulty predicting ovulation
• Acne or excess facial hair in some women with PCOS

2. Polycystic Ovary Syndrome (PCOS)

PCOS is one of the leading causes of infertility among women of reproductive age. It is a hormonal condition that can affect the normal functioning of the ovaries.

In women with PCOS, hormonal changes may interfere with regular ovulation, meaning that an egg may not be released consistently.

Common symptoms of PCOS include:

• Irregular or absent periods
• Weight gain or difficulty losing weight
• Acne
• Excess facial or body hair
• Thinning hair on the scalp
• Multiple small ovarian cysts that may be seen on ultrasound

Although PCOS can make it harder for some women to conceive, many women with PCOS do become pregnant. Lifestyle changes, medical treatment or fertility support may be recommended depending on individual needs.

3. Blocked or Damaged Fallopian Tubes

The fallopian tubes have an important role in conception because they provide the place where the sperm and egg normally meet.

When one or both fallopian tubes are blocked or damaged, fertilization may not take place, or the fertilized egg may not be able to travel properly toward the uterus.

Possible causes include:

• Pelvic inflammatory disease (PID)
• Previous pelvic infections
• Endometriosis
• Previous abdominal or pelvic surgery
• Scar tissue or adhesions
• Previous ectopic pregnancy

Some women may not notice any symptoms and only discover that their fallopian tubes are affected when they undergo a fertility evaluation.

4. Endometriosis

Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus. It can commonly affect areas such as the ovaries, fallopian tubes and surrounding pelvic tissues.

It may affect fertility in several ways, including:

• Causing inflammation
• Leading to scar tissue formation
• Blocking the fallopian tubes
• Affecting egg quality
• Changing the environment within the pelvis

Common Symptoms:

• Painful menstrual periods
• Ongoing pelvic pain
• Pain during intercourse
• Pain during bowel movements
• Heavy menstrual bleeding

However, not every woman with endometriosis experiences obvious symptoms. Some women only learn that they have the condition while being evaluated for difficulty conceiving.

5. Uterine Conditions

A healthy uterus is important for implantation and pregnancy development. Certain structural changes or abnormalities in the uterus may make successful implantation more difficult.

Examples include:

• Uterine fibroids
• Endometrial polyps
• Congenital abnormalities of the uterus
• Scar tissue inside the uterus, also known as Asherman’s syndrome

Not every uterine abnormality causes infertility. However, some may increase the possibility of implantation problems or miscarriage.

Possible Symptoms:

• Heavy menstrual bleeding
• Pelvic pressure
• Painful periods
• Repeated pregnancy loss

6. Age Related Decline in Fertility

Age is an important factor in female fertility. Women are born with a limited number of eggs, and both the number and quality of those eggs naturally decrease with age.

In general:

• 40 years and above
• Significant decline, with increased risk of chromosomal abnormalities and miscarriage

Many women still conceive naturally after age 35, but the overall likelihood of pregnancy generally decreases as age increases.

7. Premature Ovarian Insufficiency (POI)

Premature ovarian insufficiency occurs when the ovaries stop functioning normally before the age of 40.

Unlike natural menopause, ovarian function in POI can fluctuate, and some women may continue to ovulate occasionally.

Possible causes include:

• Genetic conditions
• Autoimmune disorders
• Certain medical treatments, including chemotherapy or radiation
• Unknown or idiopathic causes

Possible Symptoms:

• Irregular or absent periods
• Hot flashes
• Night sweats
• Vaginal dryness
• Difficulty conceiving

8. Hormonal Imbalances

Hormones help regulate the menstrual cycle and ovulation. Even relatively small disruptions in hormonal function can sometimes affect fertility.

Hormonal problems may involve:

• Thyroid disorders
• Elevated prolactin levels
• Pituitary gland disorders
• Hypothalamic dysfunction
• Insulin resistance, which is commonly associated with PCOS

Normal hormonal regulation is important for healthy ovulation and reproductive function.

9. Chronic Medical Conditions

Several long-term health conditions may affect fertility directly or indirectly.

Examples include:

• Diabetes
• Thyroid disease
• Autoimmune disorders
• Kidney disease
• Liver disease
• Celiac disease

Managing these conditions appropriately with medical care can help support overall reproductive health.

10. Lifestyle Factors That Can Affect Female Fertility

Daily habits can affect reproductive health. They are not always the only reason for fertility problems, but they can affect hormone levels, ovulation and overall fertility potential.

Smoking

Smoking can affect egg quality, speed up ovarian ageing and increase the risk of infertility.

Excessive Alcohol Consumption

Heavy alcohol consumption may interfere with hormonal regulation and reproductive health.

Obesity

Excess body weight may contribute to:

• Irregular ovulation
• Hormonal imbalances
• Reduced fertility
• A higher risk of pregnancy complications

Being Underweight

Having a very low body weight can also interfere with normal ovulation and menstrual cycles.

Poor Nutrition

A diet that does not provide enough essential nutrients may affect reproductive health and normal hormone production.

Chronic Stress

Stress by itself is not generally considered a direct cause of infertility, but long-term stress may influence hormone regulation, menstrual cycles and overall well-being.

Summary Table: Common Causes of Female Infertility

When Should Women Consider a Fertility Evaluation?

Every person and couple is different, but speaking with a healthcare professional may be appropriate if:

You are under 35 and have been trying to conceive for 12 months without success.

You are 35 or older and have been trying for 6 months without success.

Your menstrual periods are irregular or absent.

You have been diagnosed with PCOS, endometriosis or thyroid disease.

You have experienced repeated miscarriages.

You have a history of pelvic infections, pelvic surgery or ectopic pregnancy.

An early evaluation may help identify the cause and start appropriate care sooner.

Causes of Male Infertility, Shared Risk Factors, Diagnosis, and Prevention

Female reproductive health is only one part of conception. Male fertility matters just as much. For pregnancy to occur naturally, the man needs to produce enough healthy sperm, the sperm must be able to move effectively and they must be capable of successfully fertilizing the egg.

Male related factors contribute to a significant proportion of infertility cases, which is why assessing male fertility is an important part of a complete fertility evaluation. The encouraging part is that many causes of male infertility can be treated or managed with appropriate medical care and lifestyle changes.

Common Causes of Male Infertility

Male infertility can occur when there is a problem with sperm production, sperm quality, sperm movement, sperm transport or hormonal function.

Here are some of the more common causes.

1. Low Sperm Count (Oligospermia)

A low sperm count means the semen contains fewer sperm than expected. When fewer sperm are available to reach the egg, the chances of successful fertilization may decrease.

Low sperm count can be associated with:

• Hormonal imbalances
• Varicocele
• Infections
• Genetic conditions
• Smoking and excessive alcohol consumption
• Certain medications
• Exposure to environmental toxins

In many cases, men do not notice any obvious symptoms, and the issue may only become apparent during fertility testing.

2. Poor Sperm Motility

Sperm motility describes how well sperm move toward the egg. Even when the sperm count is normal, poor movement can make fertilization more difficult because the sperm may not reach the egg successfully.

Factors that may affect sperm motility include:

• Varicocele
• Infections

Smoking

• Excessive alcohol intake
• Exposure to heat
• Certain medical conditions

3. Abnormal Sperm Shape (Morphology)

Healthy sperm have a typical head-and-tail structure that helps them move effectively and interact with the egg.

When a large proportion of sperm have an abnormal shape, fertility may be affected.

Possible factors associated with abnormal sperm morphology include:

• Genetic factors
• Environmental exposures
• Lifestyle habits
• Certain illnesses

Although abnormal sperm morphology can affect fertility, it does not necessarily mean that a man cannot father a child naturally.

4. Varicocele

Varicocele is a relatively common and treatable cause of male infertility. It occurs when the veins inside the scrotum become enlarged, somewhat similar to varicose veins in the legs.

The enlarged veins may increase the temperature around the testicles, which can affect sperm production and sperm quality.

Possible Symptoms:

• Dull or aching pain
• Swelling in the scrotum
• Visible enlarged veins
• No symptoms in some men

5. Hormonal Imbalances

Hormones play an important role in sperm production and male reproductive health. Problems involving the pituitary gland, hypothalamus, thyroid gland or testes can interfere with normal sperm production.

Examples include:

• Low testosterone
• Thyroid disorders
• Pituitary gland disorders
• Elevated prolactin levels

Hormonal abnormalities can also affect sexual function and libido.

6. Infections

Some infections may affect fertility temporarily or permanently. They may damage parts of the reproductive tract or interfere with sperm production.

Examples include:

• Sexually transmitted infections (STIs)
• Mumps affecting the testicles, known as mumps orchitis
• Epididymitis
• Prostatitis

Identifying and treating an infection early may help reduce the risk of complications.

7. Ejaculation Disorders

Some men experience difficulties that prevent sperm from being delivered normally during ejaculation.

Examples include:

• Retrograde ejaculation, where semen moves backward into the bladder
• Delayed ejaculation
• Absence of ejaculation
• Ejaculatory duct obstruction

These conditions can reduce the likelihood of natural conception, although treatment may be possible depending on the underlying cause.

8. Genetic Conditions

Some inherited conditions can affect sperm production or the structure and function of the male reproductive system.

Examples include:

• Klinefelter syndrome
• Y chromosome microdeletions
• Cystic fibrosis-related abnormalities

Genetic testing may be suggested in selected cases depending on the individual’s medical history and fertility evaluation.

9. Previous Surgery or Injury

Past surgeries or injuries involving the reproductive organs can sometimes affect fertility.

Examples include:

• Vasectomy
• Hernia surgery
• Testicular injury
• Cancer treatment
• Pelvic surgery

Not every surgery will affect fertility, but it is important to share relevant medical and surgical history with a healthcare professional.

10. Lifestyle Factors Affecting Male Fertility

Daily habits can have a noticeable effect on sperm health.

Smoking

Smoking has been associated with lower sperm counts, poorer sperm movement and increased sperm DNA damage.

Excessive Alcohol Consumption

Heavy alcohol intake may lower testosterone levels and negatively affect sperm production.

Obesity

Being overweight may contribute to:

• Hormonal imbalance
• Lower testosterone levels
• Reduced sperm quality
• Decreased fertility
• Recreational Drug Use

Certain recreational drugs can interfere with sperm production and reproductive hormones.

Heat Exposure

Frequent or prolonged exposure to high temperatures may temporarily reduce sperm production.

Examples include:

• Hot tubs
• Saunas
• Keeping a laptop on the lap for prolonged periods
• Occupations that involve frequent exposure to high heat

Chronic Stress

Long term stress may influence hormone levels, sexual function and overall reproductive health.

Summary Table: Common Causes of Male Infertility

Causes That Can Affect Both Men and Women

Some fertility risks can affect people of either sex and can affect reproductive health in both men and women.

These include:

Increasing age

Smoking

Excessive alcohol intake

Obesity

• Poor nutrition
• Chronic stress
• Lack of physical activity
• Diabetes
• Thyroid disorders
• Certain medications
• Exposure to environmental toxins
• Sexually transmitted infections

Making healthier lifestyle choices may support overall reproductive health and may reduce some fertility risks, although lifestyle changes cannot prevent every possible cause of infertility.

Risk Factors Comparison

How Is Infertility Diagnosed?

Since infertility may involve either partner or both, healthcare professionals often recommend evaluating both individuals rather than focusing on only one person.

Evaluation in Women

Depending on the person’s symptoms and medical history, a doctor may recommend:

• Review of medical history
• Physical examination
• Assessment of ovulation
• Blood tests to check hormone levels
• Pelvic ultrasound
• Hysterosalpingography (HSG) to determine whether the fallopian tubes are open
• Additional imaging or procedures when needed

Evaluation in Men

Common investigations may include:

• Review of medical history
• Physical examination
• Semen analysis, which is often the first test
• Hormone testing
• Scrotal ultrasound
• Genetic testing when indicated
• Additional specialised tests when necessary

The tests chosen will depend on the person’s history, symptoms and examination findings.

Can Infertility Be Prevented?

Not every cause of infertility can be prevented. Factors such as age, genetics and certain medical conditions may be outside a person’s control.

Even so, adopting healthier lifestyle habits can support reproductive health and may lower the risk of some fertility-related problems.

Practical Tips to Support Fertility

Maintain a healthy body weight.

Eat a balanced diet that includes fruits, vegetables, whole grains, lean protein and healthy fats.

Stay physically active through regular exercise.

Avoid smoking and tobacco products.

Limit alcohol consumption.

Keep chronic conditions such as diabetes and thyroid disorders under appropriate medical management.

Practice safe sex to reduce the risk of sexually transmitted infections.

Make sure you get enough quality sleep.

Find healthy and practical ways to manage stress.

Avoid unnecessary exposure to environmental toxins whenever possible.

Fertility Health Flowchart

When to Seek Help, Supporting Fertility, FAQs & Conclusion

When Should You Consult a Fertility Specialist?

Trying for a baby can be emotional, and every couple’s experience is different. It is normal for pregnancy to take some time, but there are situations were seeking medical advice sooner can help identify possible concerns and provide appropriate guidance.

You should consider consulting a healthcare professional if:

For Women

You are under 35 and have been trying to conceive for 12 months without success.

You are 35 or older and have been trying to conceive for 6 months without success.

Your menstrual periods are irregular, absent or very painful.

You have been diagnosed with PCOS, endometriosis or a thyroid disorder.

You have experienced multiple miscarriages.

You have undergone pelvic surgery or had a pelvic infection.

You have previously experienced an ectopic pregnancy.

For Men

You have a history of low sperm count.

You have experienced a testicular injury or undergone testicular surgery.

You have received chemotherapy or radiation therapy.

You have difficulty with sexual function or ejaculation.

You have a history of undescended testicles or varicocele.

You have been diagnosed with a hormonal or genetic condition that may affect fertility.

Getting evaluated early can help identify possible causes and provide a clearer idea of what steps may be appropriate next.

Supporting Fertility Through a Healthy Lifestyle

Although some causes of infertility cannot be prevented, healthy daily habits can support reproductive health as well as overall well-being.

Eat a Balanced Diet

A balanced diet provides the vitamins, minerals, antioxidants, healthy fats and protein the body needs for normal functions, including reproductive health.

Try to focus on:

• Fresh fruits and vegetables
• Whole grains
• Lean sources of protein
• Healthy fats
• Adequate hydration

Maintain a Healthy Weight

Both obesity and being underweight can affect hormone regulation and reproductive function.

Maintaining a healthy body weight through balanced nutrition and regular physical activity may support fertility in both men and women.

Stay Physically Active

Moderate exercise supports overall health and may also help with hormone regulation and stress management.

Aim for regular, manageable exercise while avoiding excessive or extreme exercise, which may negatively affect fertility in some individuals.

Avoid Smoking and Limit Alcohol

Smoking and excessive alcohol consumption have been associated with reduced fertility in both men and women.

Avoiding tobacco products and keeping alcohol intake limited are practical steps that can support overall reproductive health.

Manage Stress

Stress is not usually considered a direct cause of infertility, but finding ways to manage it can support emotional well-being during what can be a challenging fertility journey.

Some approaches that may help include:

• Meditation
• Yoga
• Deep breathing exercises
• Walking
• Spending time with family and friends
• Seeking counselling or joining support groups when needed

Get Enough Sleep

Enough sleep supports hormone regulation, physical health and mental well-being.

Adults should generally aim for around 7-9 hours of quality sleep each night.

Supporting Reproductive Wellness

Reproductive health is influenced by several factors working together, including appropriate medical care, healthy lifestyle habits, balanced nutrition, regular physical activity, adequate sleep and stress management.

For some people, a healthcare professional may also recommend nutritional support depending on their overall health, dietary intake and individual requirements.

Products such as Zeniqua Ovibliss, developed to support women’s reproductive wellness, and Zeniqua Mantrix, formulated for men’s reproductive health, may be considered as part of a broader wellness approach when used with appropriate guidance from a healthcare professional.

Dietary supplements should be viewed as support for, not a replacement for, a healthy lifestyle. They should not replace medical evaluation, diagnosis or infertility treatment. Anyone who is having difficulty conceiving should speak with a qualified healthcare professional to identify the possible underlying cause and discuss the most appropriate options for management.

Frequently Asked Questions (FAQs)

1. What is the most common cause of infertility?

Infertility does not have one universal cause. Among women, ovulation problems such as PCOS are common causes, while in men, low sperm count and reduced sperm quality are frequently identified. In some situations, fertility difficulties may involve factors affecting both partners.

2. Can infertility affect both men and women?

Yes. Infertility may result from male factors, female factors, a combination of factors in both partners, or sometimes no specific cause even after a detailed evaluation.

3. Can lifestyle habits influence fertility?

Yes. Healthy lifestyle choices can support reproductive health. Factors such as smoking, excessive alcohol intake, obesity, poor nutrition and certain environmental exposures may negatively affect fertility in both men and women.

4. Is infertility always permanent?

No. Many causes of infertility can be treated or managed. Depending on the underlying cause, medical treatment, lifestyle changes or assisted reproductive techniques may improve the chances of achieving pregnancy.

5. Is infertility always permanent?

No. Infertility is not necessarily permanent. Many causes can be treated or managed, and the appropriate treatment depends on what is causing the fertility problem. Depending on the situation, treatment, lifestyle changes or assisted reproductive techniques may improve the possibility of pregnancy.

Nidhi

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