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Causes of female infertility

What Are Some of The Causes of female infertility?

By Dr Harry Hiniadis

Infertility is defined as the inability to conceive despite regular and unprotected intercourse for more than one year. However, risk factors such as the woman’s age, abnormal menstrual periods, history of pelvic inflammatory disease or previous abdominal or pelvic surgery, may warrant earlier investigations.

Incidence of female infertility

Infertility affects one in seven couples and affects both men and women. It is important to remember that the majority of infertile couples can achieve a pregnancy and birth with treatment. Only a minority of patients are sterile, i.e. unable to conceive with treatment.
Infertility is classified into two types:

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  • Primary female infertility if there was no previous pregnancy (approximately 40% of infertile couples).
  • Secondary infertility if there was a previous pregnancy whatever the outcome (approximately 60% of infertile couples).


Endometriosis refers to a benign and common disease in which cells like the ones that line the inside of the womb are established outside the womb. In patients with endometriosis, these cells, like the endometrium, respond to the monthly hormonal changes.

When a woman with endometriosis menstruates, the endometrium is shed in the form of a period, the endometriosis breaks down in the same way but as these cells are trapped inside, and cannot escape, they swell and fill with dark blood (known as chocolate cysts) and adhesions which may damage the tubes.

Endometriosis tends to occur in women who are in their 30s/early 40s, but occasionally occurs in those under 30. Some patients may have no symptoms whilst others may experience considerable pain during their periods or during intercourse with periods being heavy.

On vaginal examination there may be tenderness and thickening of the supporting ligaments of the uterus. The majority of women with endometriosis are fertile however some may experience difficulty becoming pregnant.

How does endometriosis cause infertility?

The anatomical distortion caused by endometriosis could explain a mechanical cause of female infertility although the precise mechanism by which minimal and mild endometriosis affects fertility is not fully understood. It is possible that endometriosis could adversely affect egg development, sperm binding to the egg, fertilization, tubal function and embryo implantation.


The only means of diagnosis is by laparoscopy. There are a number of different classification systems for endometriosis, but the most widely used is that of the American Society for Reproductive medicine (ASRM) in which it is classified into four stages: minimal, mild, moderate and severe. There is little correlation between the severity of symptoms and extent of the endometriosis.

Ultrasound scans, CAT scans, or MRI scans, can identify cysts on the ovaries. However, these techniques cannot be used to make a definitive diagnosis of endometriosis.


Cause is unknown however the most widely accepted explanation for endometriosis is that viable cells from the lining of the womb pass upwards into the Fallopian tube and out into the pelvic cavity where they settle down.

Ovulation problems

This is the most common cause of female infertility and it is also the one with the best chance of successful treatment. The woman usually presents with infrequent or very scanty periods, irregular periods or absent periods altogether (amenorrhoea). However, ovulation dysfunction can occur with apparently regular cycles.

Ovulation disorders can be classified into:

  • Annovulation i.e. lack of ovulation
  • Oligoovulation i.e. infrequent ovulation
  • Luteal phase defects


Primary. The problem is in the ovary itself e.g. either the ovaries were surgically removed; they were damaged by radiotherapy or chemotherapy treatment for cancer; they only have a few eggs in them i.e. premature menopause or where the woman was born without ovaries. Ovulatory problems can occur as a result of hormonal imbalance. This imbalance may arise either within the hypothalamus, the pituitary gland, or in the ovaries. Common causes of this include stress, weight loss or weight gain, excessive prolactin production (the hormone that stimulates milk production) and polycystic ovarian disease.

Polycystic Ovaries

About 20% of women have polycystic ovaries (PCO). This term describes the appearance, as seen on an ultrasound scan of an increased number of small cysts on the surface of the ovary. Many women with PCO have normal regular cycles and have no problems conceiving. Some women however with these ultrasound findings have a condition known as polycystic ovarian disease (PCOD). These women have a hormone imbalance with irregular or absent periods and they may have difficulty conceiving.

Treatment firstly involves the use of drugs to correct the hormone imbalance and to stimulate ovulation. If the woman is obese, weight loss may also improve the hormonal imbalance. Alternatively, a laparoscopy, ovarian drilling (making tiny holes on the surface of the ovaries using diathermy or laser) may be performed prior to an IVF cycle.


Here, the ovaries are not the problem, but the lack of hormones released from the pituitary gland or hypothalamus. Causes include stress; weight gain or loss; certain drugs; excess production of the hormone prolactin and disturbances involving the thyroid gland and the adrenal glands. Some women have antibodies against sperm within their mucus and in these women, even at the time of ovulation, sperm are often unable to pass through the cervical canal.

Tubal problems

Tubal damage is a common cause of infertility. Damage to the fimbriae may reduce or stop the ability to pick up the egg and direct it into the Fallopian tube. Blockage of the tube can prevent the sperm from reaching the egg, or the fertilized egg from moving to the uterus and increases the incidence of ectopic pregnancy. Tubal blockage can be either proximal or distal. The former is where the blockage is located close to the uterus, while the latter is where it lies at the fimbriae.

Causes Infection

This could result from a previous pelvic infection; sexually transmitted diseases such as chlamydia and gonorrhoea; infections from internal organs; or after an abortion, miscarriage or delivery.


Any surgery that involves the Fallopian tubes, ovaries and uterus can cause adhesions.


Endometriosis can lead to scarring of the tubes, adhesions, and in severe cases to blockage of the tubes.


Hydrosalpinx is a blocked, dilated, fluid filled Fallopian tube usually caused by a previous pelvic infection. In mild cases fertility may be restored by opening the tube surgically, otherwise IVF is the treatment of choice

Unexplained infertility

Unexplained infertility affects 20-25% of infertile couples. In the majority of these cases, the failure to reach a diagnosis is not due to inadequate investigations, but is probably due to other factors, which cannot be assessed using conventional tests. In cases of unexplained infertility, assisted conception in the form of IVF is both diagnostic and therapeutic.

The relationship between age and fertility

Delayed child bearing is becoming increasingly common but although pregnancies in women approaching 50 and beyond are occasionally reported, there is a decrease in fertility with advancing age. The decline is gradual over the reproductive life span of the woman; it is particularly noticeable over the age of 30 and accelerates between 35 and 40 so that fertility is almost zero by the age 45.

The risk of miscarriage is also increased with ageing e.g. the risk of miscarriage at age 25-29 years is 10% while the risk at age 40-44 is 34%. Furthermore, advanced maternal age is associated within increased risk of chromosomally abnormal offspring.

Why does fertility decline with age?

Ageing of the ovaries is the most prominent factor and is part of the normal ageing changes that affect all organs and tissues. Most women have about 300,000 eggs in their ovaries at puberty.

For each egg that matures and is released (ovulated) during the menstrual cycle, at least 500 eggs do not mature and are absorbed by the body. By the time the woman reaches menopause which usually occurs between 50-55 years, there are only several thousands eggs remaining. As the woman ages, the remaining eggs in her ovaries also age, making them less capable of fertilisation.

The risk of a chromosomal abnormality in a woman age 20 years is 1/500 while the risk in woman age 45 is 1/20. Gynaecological problems such as pelvic infection, tubal damage, endometriosis, fibroids, ovulation problems etc tends also to increase with age.

As the woman gets older, she has more time to develop these conditions, which will adversely affect her fertility.

Several tests may be useful in assessing the fertility potential in older woman e.g. blood tests to examine the levels of the hormones FSH, LH, oestradiol and inhibin on day 3 of your menstruation.

You will be more likely to be counselled about the risk of miscarriage and chromosomal abnormalities in relation to your age. In addition to the potential complications of pregnancy such as high blood pressure, bleeding and diabetes.

The treatment options for older women who are menopausal or peri-menopausal include IVF and egg donation.

This overview was written by Dr Harry Hiniadis, Reproductive Gynaecologist, a Medical Advisor for Redia IVF Travel, one of the Fertility Road Journey partners.

Editorial Team
Editorial Team
Fertility Road aims to inform and inspire in a way that is direct, honest and empathetic, whilst breaking down the science by being written by top experts from the fertility field.

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15 articles about IVF and Donor Conception by top IVF experts worldwide!