A specialist’s guide to fertility

Written by: Dr Anusha Dias
Published: | Updated: 25/03/2019
Edited by: Top Doctors®

85 couples out of 100 who have regular unprotected sexual intercourse conceive within one year. Around 1 in 7 couples, which is roughly 3.5 million people in the UK, have difficulty in conceiving. As part of National Fertility Awareness Week, we asked Dr Anusha Dias, an expert in sexual and reproductive healthcare and psychosexual medicine, to explain more about infertility and its various causes.


Primary & secondary infertility

Infertility is diagnosed when a couple have not conceived after one year of regular unprotected sex. There are two types of infertility – primary infertility, and secondary infertility. Primary infertility refers to when a couple has never been able to conceive and secondary infertility refers to when a couple has able to get pregnant at least once in the past.

Many factors can cause infertility and it can be due to issues with the man, the woman, or perhaps both.

When trying to conceive, it is important to lead a healthy lifestyle, stop smoking and drinking alcohol, maintain a healthy body weight, and to try as much as possible to reduce stress.

Some common causes of infertility

Ovulatory factors

Ovaries release eggs in a process called ovulation, which is controlled by several hormones working in conjunction. Ovulatory dysfunction occurs when ovulation does not occur regularly or correctly. Ovulatory disorders are one of the most common reasons for difficulties with conception, and this is often due to polycystic ovarian syndrome or PCOS. Other factors causing ovulatory dysfunction include obesity, anorexia, hormonal imbalances due to disorders in the pituitary or thyroid, drug use, stress and sometimes endometriosis.


Women are born with all their eggs and do not produce eggs throughout their lifetime. A woman’s fertility declines steadily as she gets older, particularly in her 30s and especially after the age of 38. Older women are at greater risk of miscarriage and other complications. Male fertility also declines with age, but to a lesser extent.

Structural issues

Another cause of infertility can be due to structural abnormalities which alter the shape of the uterus or womb. This can occur as a result of large fibroids or because a woman is born with an unusual shaped uterus such as a bicornuate uterus.

The egg which has been released by the ovary needs to travel along the fallopian tubes to fertilise with the sperm and so a partial or complete blockage of the fallopian tubes can result in infertility. This can be occur due to sexually transmitted infections such as Chlamydia. If a woman has Chlamydia once then there is a 12% risk of infertility and if this happens twice then the risk increases to almost 30%.

Endometriosis is a common condition where tissue that behaves like the lining of the uterus migrates to other parts of the body. This can damage the fallopian tubes, ovaries and can cause scarring in the womb and abdominal cavity.  

Male factor

Male infertility can be caused by a wide range of disorders and factors which alter sperm count, sperm quality or movement (motility), such as infections, structural abnormalities such as a varicocele (an abnormal enlargement of veins in the scrotum), testicular problems including cancer or as a result of trauma to the testes, and hormone imbalances

Other factors such as age, weight, drinking, smoking, stress, drug use and exposure to high heat for prolonged periods of time can also affect male fertility.

Learn all about male infertility here


Unexplained infertility is given as a diagnosis when a couple cannot conceive but no cause can be identified. This happens in a quarter of all cases and it is very difficult to come to terms with as all the fertility tests are normal, and there is no obvious ‘problem’ but they cannot conceive.

Sexual issues

If a couple are not able to have regular sexual intercourse, especially when an egg is released, then this can lead to infertility. One example of this is when a woman is experiencing vaginismus or when sexual intercourse is very painful.

Sexual dysfunction can also occur after an infertility diagnosis as the process of assisted reproduction and fertility treatments can sometimes cause high stress and anxiety along with potential repeated failed attempts to conceive.


This is a term used to describe difficulties in conceiving as a result of multiple factors; for example, ovulatory dysfunction in the presence of a male factor. Occasionally treatment of one of the causes results in conception, but more often couples with multifactorial cause of infertility need some form of assisted conception particularly if they have been trying to conceive for more than 3 years or if the female patient is older.

Dr Anusha Dias

By Dr Anusha Dias
Obstetrics & gynaecology

Dr Anusha Dias is a consultant in sexual and reproductive healthcare and psychosexual medicine. She is the lead for psychosexual medicine at London North West University Health Care NHS Trust and also practices at the Clementine Churchill Hospital. She is an empathetic doctor with extensive expertise in two areas. One is in psychosexual medicine which includes psychological issues in obstetrics and gynaecology, such as pain with sex, and she provides comprehensive integrated care for women with sexual difficulties resulting in infertility including vaginismus and non-consummation. Her other area of expertise is non-operative gynaecology and she is an expert in all methods of contraception including insertion of IUDs/IUS, implants, gynaecological screening, HPV vaccine and vaginal discharge.

Dr Dias has a particular interest in undergraduate and postgraduate education and runs nationally recognised courses for the Faculty of Sexual and Reproductive Healthcare and is a regional training advisor. She has published extensively and lectures widely. She is on the advisory board of Sexplain, a not-for-profit organisation that provides educational workshops for young people.

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