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What are the causes of infertility?

If you’re trying to conceive without success, it can be upsetting and frustrating, especially when you don’t know what the issue is.

Here are some of the most likely causes of fertility problems, with suggestions for possible next steps you can take.

Find out about the fertility assessments we offer at TFP Fertility UK, and when to see a specialist.

What are the causes of infertility?

What is infertility?

Infertility is defined as when a couple have regular unprotected sex for a year or more and don’t get pregnant.

Around 84% of couples will conceive naturally within a year if they have unprotected sex every two or three days.

But one in seven couples have difficulty conceiving.

There are two types of infertility:

  • Primary infertility – where a man or woman who’ve never conceived a child before have difficulty conceiving

  • Secondary infertility – where a man or woman who’ve had one or more pregnancies in the past but haven’t been able to conceive again

We recommend you seek advice if you’ve been trying to get pregnant for over a year, or sooner if you think there might be an underlying problem.

What are the causes of infertility?

There are many possible reasons why a man or woman may be infertile but in around a quarter of cases, it’s not possible to identify an exact cause.

Apart from age, there are several lifestyle factors that can affect your overall fertility, including:

  • Being overweight or obese

  • Sexually transmitted infections (STIs)

  • Smoking

  • Drinking too much alcohol

  • Stress

Getting started contact us

Speak to us today

If you have any questions or concerns about your fertility, or would like to book an appointment at your local TFP Fertility clinic, please contact us.

No matter where you are in your fertility journey, we’re here with you every step of the way.

Common causes of infertility in women

Age and egg quality

The most common reason for infertility in a woman is their age.

Research shows that the quality of a woman’s eggs starts to decline after 35, and significantly so after the age of 40.

Ovulation problems

Some ovulation problems stop any eggs being released from the ovaries, while other issues prevent an egg being released during some menstrual cycles.

Ovulation problems can be caused by:

  • Polycystic ovary syndrome (PCOS) – the main features of PCOS are irregular periods, high levels of male hormones in the body, and fluid-filled sacs surrounding the eggs

  • Overactive or underactive thyroid gland

  • Premature ovarian failure – when the ovaries stop functioning properly before the age of 40

Fallopian tubes and womb problems

Your fallopian tubes carry eggs from your ovaries to the womb and, if they’re blocked or damaged, it can cause fertility issues.

Fallopian tubes and womb problems can be caused by:

  • Scarring from surgery, such as a C-section

  • Fibroids – non-cancerous growths in or around the womb that may block the fallopian tube or prevent a fertilised egg attaching to the womb lining

  • Endometriosis – a condition where tissue similar to the lining of the womb grows in other places, such as the ovaries

  • Pelvic inflammatory disease – often caused by a sexually transmitted infection (STI), this affects the womb, fallopian tubes, and ovaries


Medicines and drugs that can affect a woman’s fertility include:

  • Chemotherapy to treat cancer

  • Non-steroidal anti-inflammatory drugs such as ibuprofen and aspirin

  • Antipsychotic medicines can sometimes cause missed periods or infertility

  • Spironolactone (aka Aldactone), which is used to treat fluid retention

  • Prescribed medicinal cannabis

Common causes of infertility in men

Sperm quality

Reasons for low-quality sperm include:

  • Low numbers or no sperm in the semen

  • Sperm that do not swim properly, making it hard for them to reach an egg

  • Sperm with an abnormal shape, size or appearance

Problems with testicles

The testicles produce and store sperm.

If a man’s testicles are damaged, it can affect the quality of their semen.

Testicles may become damaged because of:

  • Infection

  • Surgery

  • Cancer

  • Injury

Blocked tubes

Sometimes the tubes that sperm travels through can become blocked, preventing sperm from leaving the testicles.

Tubes may become blocked due to:

  • Infection

  • Surgery

  • Swelling

  • Problems with the way the tubes have developed


Medicines and drugs that can affect a man’s fertility include:

  • Chemotherapy to treat cancer

  • Sulfasalazine (aka Azulfidine) – an anti-inflammatory medicine that can temporarily affect numbers of sperm

  • Anabolic steroids

  • Some herbal remedies

  • Prescribed medicinal cannabis

What infertility tests can I have?

At TFP Fertility UK, we offer fertility assessments for individuals and couples that provide a quick and accurate measure of fertility.

We’ll sensitively discuss the problems you’re experiencing and arrange for you to have some tests.

Then, once we’ve identified what might be affecting your fertility, we’ll be able to create a treatment plan tailored to your specific needs.

How can infertility be treated?

There are three main types of treatment for infertility:


For women, following your diagnostic tests, your GP may prescribe you fertility medicines to encourage ovulation or treat PCOS.


There are several types of surgical procedures that can help to solve fertility problems.

For women, these include:

  • Fallopian tube surgery to repair blocked or scarred tubes

  • Keyhole surgery to treat endometriosis, fibroids or PCOS

For men, surgical procedures to help with fertility include:

  • Unblocking the epididymis – the tightly coiled tube in the testicles that helps to store and transport sperm

Fertility treatment

At TFP Fertility, we offer a range of fertility treatments to help people conceive and have the families they long for, including intrauterine insemination (IUI) and in vitro fertilisation (IVF).

We combine 35 years of fertility experience with care that’s second to none.

Whatever your situation and wherever you are in your fertility journey, we’ll work with you to develop a personalised treatment and care plan that optimises your chances of success and helps you manage the ups and downs of the experience.

TFP nurse

Contact us today

If you’d like to book an appointment to discuss your fertility at TFP Fertility UK clinic, please contact us today.

We’ll get back to you within 48 hours and provide you with all the information you need to begin your journey with TFP Fertility UK.

Frequently asked questions

Here we answer some of the questions people most often ask us. If you want to know more, contact our friendly, expert team today for a confidential chat and to book an appointment with one of our fertility experts.

What are the signs of infertility?

For women, the main sign of infertility is not being able to get pregnant.

Sometimes, women with fertility problems may have irregular periods or no periods at all.

Again, for men, the main sign is not being able to conceive a child.

A man’s fertility is also linked to his hormone health, which means changes in hair growth and sexual function can be an indicator of infertility.

Why have my periods stopped?

There are many reasons why a woman’s period might stop, but in each case, it’s important to make an appointment with your GP.

The most common reasons are:

  • Pregnancy

  • Stress

  • Sudden weight loss

  • Being overweight

  • Too much exercise

  • Taking the contraceptive pill

  • Menopause

  • Polycystic ovary syndrome (PCOS)

Can an abortion cause infertility?

If you have an abortion, it will not usually affect your chances of becoming pregnant.

You should be able to have normal pregnancies in the future.

But there is a very small risk that you may develop a womb infection during your procedure. If this isn’t treated properly, it could cause a risk to your fertility and future pregnancies.

Can herpes cause infertility?

Herpes doesn’t harm female fertility in the same way some sexually transmitted diseases can.

A study has shown that herpes may lead to a lower sperm count in men, but it won’t cause infertility.

Can mumps cause infertility?

Around one in 20 women who have mumps after puberty experience oophoritis, a swelling of the ovaries that causes lower stomach pain, sickness, and a high temperature.

But this is not known to lead to fertility issues.

According to the NHS, 25% of men who have mumps after puberty will develop orchitis, which causes pain and swelling in one or both of the testicles.

For a small percentage of men, orchitis will lead to a decrease in the size of the affected testicles.

This may reduce a man’s sperm count, but it will not lead to infertility.

Can chlamydia cause infertility?

If left untreated, chlamydia can lead to damage of a woman’s reproductive system, including the fallopian tubes and uterus, which can lead to infertility.

Untreated chlamydia can also damage the male reproductive system and lead to infertility.


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