What Causes Infertility in Women? Common Reasons Fertility Can Be Affected

March 25, 2026

Female infertility can happen for many different reasons, and often several factors are involved

For many women, fertility problems are not obvious until pregnancy takes longer than expected. In some cases there are clear medical causes, while in others fertility investigations are needed before a cause becomes clear.

Female infertility can involve ovulation, hormones, reproductive anatomy, age, or underlying health conditions.

Understanding the most common causes helps explain why fertility testing is often recommended early.


Ovulation Problems

One of the most common female infertility causes is difficulty releasing eggs regularly.

Ovulation may be irregular or absent, which reduces the chance of conception.

Signs ovulation may be affected include:

  • irregular menstrual cycles
  • very long cycles
  • absent periods
  • unpredictable bleeding patterns

Hormonal imbalance often affects ovulation.


Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome is one of the most common causes of ovulation-related infertility.

It can affect:

  • ovulation frequency
  • hormone balance
  • egg development

Common symptoms include:

  • irregular periods
  • acne
  • excess hair growth
  • difficulty losing weight

Many women with PCOS conceive successfully with treatment.


Endometriosis and Fertility

Endometriosis can affect fertility by causing inflammation, scar tissue, and changes around the ovaries or fallopian tubes.

It may lead to:

  • painful periods
  • pelvic pain
  • pain during intercourse
  • reduced fertility

Some women with endometriosis conceive naturally, while others may need fertility treatment.


Blocked Fallopian Tubes

The fallopian tubes carry eggs from the ovaries to the uterus.

If the tubes are blocked or damaged, sperm and egg may not meet.

Possible causes include:

  • previous infection
  • pelvic inflammation
  • endometriosis
  • previous surgery

Tubal problems are often identified through fertility testing.


Age-Related Fertility Decline

Age is one of the most important fertility factors.

Female fertility naturally declines over time because:

  • egg number reduces
  • egg quality changes

This decline becomes more noticeable after 35.

Even with regular cycles, fertility can still be affected by age.


Hormonal Imbalance

Several hormones control ovulation and reproductive function.

When hormones are disrupted, fertility may be affected.

Possible hormone-related causes include:

  • thyroid imbalance
  • raised prolactin
  • low ovarian reserve

Hormone blood tests often help identify this.


Low Ovarian Reserve

Low ovarian reserve means the number of remaining eggs is lower than expected for age.

This is often assessed using:

  • AMH blood testing
  • ultrasound follicle count

It does not automatically mean pregnancy is impossible, but it may affect treatment planning.


Uterine Conditions

Some uterine conditions can affect implantation or pregnancy development.

Examples include:

  • fibroids
  • polyps
  • structural abnormalities

These are often detected through scans.


Unexplained Infertility

Sometimes all fertility tests appear normal, but pregnancy still does not happen.

This is called unexplained infertility.

It means:

  • no clear medical cause has been identified
  • fertility treatment may still help

This diagnosis is common and can still lead to successful pregnancy.


When to Seek Fertility Advice

It may be helpful to seek medical advice if:

  • you have been trying for 12 months
  • cycles are irregular
  • periods are absent
  • there is known reproductive health history
  • age is becoming a concern

Women over 35 often seek advice sooner.


Fertility Tests That May Be Recommended

Doctors may suggest:

  • hormone blood tests
  • ovulation tracking
  • ultrasound scans
  • fallopian tube testing

These help identify what treatment may help most.


Treatment Options for Female Infertility

Treatment depends on the cause.

Options may include:

  • ovulation medication
  • surgery
  • hormone treatment
  • IVF treatment

When IVF becomes part of treatment, financial planning can also become important.

The Fertility Foundation supports eligible applicants seeking fertility support and IVF grant guidance.


Frequently Asked Questions

Can stress cause infertility?

Stress alone does not usually cause infertility, but it can affect cycles and overall wellbeing.


Can you have regular periods and still be infertile?

Yes, regular periods do not always mean ovulation and fertility are unaffected.


Is infertility always permanent?

No, many fertility problems are treatable.


When should I worry about not getting pregnant?

If pregnancy has not happened after 12 months, fertility advice is often recommended.


 Infertility affects many individuals and couples, but understanding the causes female infertility is the first step toward finding support