What are the most common reasons for infertility?

Ready to start a family? Falling pregnant should be easy! In theory yes, however many factors have to come together in order for conception to happen and you’d be surprised at how many individuals and couples suffer from infertility.

It is thought that around one in six couples have difficulty conceiving – this is approximately 3.5 million people in the UK. Most commonly, infertility is associated with approximately 30% female fertility factors arising from ovulatory problems, 30% male fertility factors such as poor quality sperm and 40% are unexplained or a combination of factors.

For natural conception to occur the female partner must produce an egg from one of her ovaries, which is then fertilised by high quality sperm from the male partner. Regular intercourse every two to three days will increase the chances of fertilisation. Once fertilisation has occurred, the embryo must implant and develop inside the uterus. If any of these processes are compromised at any stage, the chance of a natural conception is decreased, and in some cases, even impossible.

What is infertility?

Infertility is defined as the inability to achieve a pregnancy after 12 months or more of regular, unprotected intercourse. Infertility can affect both men and women and is far more common than most people realise. However, most causes of infertility are receptive to fertility treatment, and we here at IVF-Life UK can assist in diagnosing the cause of your infertility and tailor the appropriate treatment plan for you.

What are the causes of infertility in women?

In women, a number of factors can disrupt the process of conception at any step. Female infertility is usually caused by one or more of the following factors:

Ovulation Disorders 

Ovulation disorders, meaning you ovulate infrequently or not at all are amongst the most common causes of infertility in women, accounting for about  1 in 4 infertile couples. Caused by problems with the regulation of reproductive hormones, ovulation disorders are defined as disturbances in the production of an egg during a woman’s menstrual cycle.

  • Polycystic Ovary Syndrome (PCOS)
    PCOS causes a hormone imbalance, which affects ovulation. PCOS is associated with insulin resistance and obesity, abnormal hair growth on the face or body, and acne. It is the most common cause of female infertility.
  • Premature Ovarian Failure
    Also known as primary ovarian insufficiency, this disorder is usually caused by an autoimmune response or by premature loss of eggs from your ovary (possibly from genetics or chemotherapy). The ovary no longer produces eggs, and it lowers oestrogen production in women under the age of 40.
  • Hypothalamic Dysfunction
    Two hormones produced by the pituitary gland are responsible for stimulating ovulation each month- follicle stimulating hormone (FSH) and luteinising hormone (LH). Excess physical or emotional stress, a very high or very low body weight, or a recent substantial weight gain or loss can disrupt the production of these hormones and affect ovulation. Irregular or absent periods are the most common signs.
  • Too much Prolactin
    The pituitary gland may cause excess production of prolactin (hyperprolactinemia), which reduces oestrogen production and may cause infertility. Usually related to a pituitary gland problem, this can also be caused by medications you are taking for another disease.


Endometriosis is a condition where cells similar to the ones in the lining of the uterus are found elsewhere in the body. Each month these cells react in the same way to those in the uterus, building up and then breaking down and bleeding. Unlike the cells in the uterus that leave the body as a period, this blood has no way to escape.

The extra tissue growth, and the surgical removal of it, can cause scarring, which may block fallopian tubes and prevent an egg and sperm from uniting. Endometriosis can also affect the lining of the uterus, disrupting implantation of the fertilised egg. The condition also seems to affect fertility in less direct ways, such as damage to the sperm or egg.

Damage to Fallopian Tubes (Tubal Infertility)

Damaged or blocked fallopian tubes prevent sperm from getting to the egg or block the passage of the fertilised egg into the uterus. Causes of fallopian tube damage or blockage can include:

  • Pelvic Inflammatory Disease, an infection of the uterus and fallopian tubes due to chlamydia, gonorrhoea or other sexually transmitted infections.
  • Previous surgery in the abdomen or pelvis, including surgery for ectopic pregnancy, in which a fertilised egg implants and develops in a fallopian tube instead of the uterus.

Uterine or Cervical Causes

Several uterine or cervical causes can impact fertility by interfering with implantation or increasing the likelihood of miscarriage:

  • Benign polyps or tumours (fibroids or myomas) are common in the uterus. Some can block fallopian tubes or interfere with implantation, affecting fertility. However, many women who have fibroids or polyps do become pregnant.
  • Endometriosis scarring or inflammation within the uterus can disrupt implantation.
  • Uterine abnormalities present from birth, such as an abnormally shaped uterus, can cause problems becoming or remaining pregnant.
  • Cervical Stenosis, a narrowing of the cervix, can be caused by an inherited malformation or damage to the cervix.
  • Sometimes the cervix can not produce the best type of mucus to allow the sperm to travel through the cervix into the uterus.

Unexplained Fertility

Sometime, the cause of infertility is never found. A combination of several factors in both partners could cause overcoming unexplained infertility problems. Although it is frustrating to get no specific answer, this problem may correct itself in time. But, you shouldn’t delay the treatment for infertility.

What are the causes of infertility in men?

Sperm Disorders

The most common reason for male infertility is a problem with your sperm. It may be that:

  • You don’t have enough sperm in your semen
  • Your sperm don’t move as fast as they need to
  • Your sperm are the wrong shape

You may have all three of these problems at the same time .

Some men have no sperm at all in their semen. This is usually caused by a condition called azoospermia. The tubes that carry sperm from your penis are blocked. You may be born with this or you may develop it after an infection, bladder neck surgery or scarring after an inguinal hernia repair.


If you have hypogonadism, you don not produce enough, or any, of the hormone testosterone. This may affect your sperm count, or mean you can’t get an erection and have a low sex drive.

You can have hypogonadism from birth or develop it after an illness or accident. You may also develop it if you’re taking certain medications such as spironolactone (a water tablet or diuretic), and cimetidine (an antacid).

Ejaculation Disorders

Several problems can affect how you ejaculate (release semen).

  • Erectile Dysfunction, this is where you can’t keep an erection for long enough to have sexual intercourse.
  • Retrogade Ejaculation, where your semen is ejaculated backwards into your bladder rather than out of your body.
  • Delayed Ejaculation means you can’t ejaculate inside your partners vagina. This may be a psychological problem.
  • Anorgasmia, this is where you do not reach an orgasm and ejaculate. This may be because you don’t have enough feeling in your penis (sometimes caused by nerve damage).

Other factors affecting fertility in both men and women:

Age – Female and male fertility to a lesser extent does decline with age. This is particularly so for women whose fertility starts to decline after the age of 35 .

Weight – Being overweight or obese reduces your fertility. We recommend a BMI of under 30to give you an optimal chance of success.

Alcohol – The safest approach for women is not to drink if planning to get pregnant and for men too much alcohol can affect sperm quality. Once pregnant women should avoid drinking alcohol altogether.

Smoking – Can affect chances of conceiving in women and reduce sperm quality in men.

Stress – In severe cases stress can affect ovulation and sperm production. In lesser a loss of sex drive.

How we can help

First and foremost, at IVF-Life UK we can provide comprehensive fertility assessments, from one off sperm and AMH tests, to more in-depth investigations, cycle monitoring and testing.

Whether you’re looking to assess your chances of naturally conceiving or you’re interested in learning more about why you may be struggling, our tests can explain yours or your partner’s fertility situation.

This will then allow our expert consultants to provide honest and accurate recommendations on your chances of successful conception, either naturally or through fertility treatment. We can carefully tailor a personalised treatment plan, offer one to one care and support you through every stage of your fertility journey.

If you would like to arrange a consultation to discuss your own fertility journey, or arrange a fertility assessment, please get in touch and our patient services team will look after you every step of the way. You can call us on 01925 202180 or contact us here.