What are fibroids and how they can be treated to assist with pregnancy?

What are fibroids?

Fibroids are non-cancerous tumours that grow in or around the uterus (womb), usually in the outer muscular layer (myometrium). The growths are made up of muscle and fibrous tissue and can vary in size. Fibroids are often called leiomyomas or uterine myomas.

What are the symptoms of fibroids?

Clinical studies research published in 2015 showed that fibroids are very common; between 50-77% of women have fibroids. Fibroids can have no symptoms at all but they can also cause heavy periods, painful periods, abdominal or lower back pain, constipation, pain during sex and can sometimes be linked to infertility including recurrent miscarriage or problems during pregnancy. In women with symptomatic fibroids, heavy periods stop at menopause, fibroids can shrink and many other symptoms will subside at this point. 

Fibroids are often suspected in premenopausal women that have some of the above symptoms and an enlarged uterus or mass can be felt when a pelvic examination is performed. A more definitive diagnosis can be easily confirmed using ultrasound. More specific information about the type and extent of the fibroids can be gained using an imaging technique called magnetic resonance imaging (MRI).

What are the risk factors for fibroids?

A number of risk factors have been linked with fibroids, these include the following: An older age at menopause, a younger age at which a women’s periods began, the use of hormonal contraceptives before the age of 16, a high body mass index and some specific genetic mutations. Fibroids are also more common in women of the black race.

There are also a number of factors that have been linked with a decreased risk of developing fibroids: Having more children, using progestin-only injectable contraceptives, having a diet that is high in fruit, vegetables and low-fat dairy products. 

How can fibroids be treated?

The size, number, location and symptoms of fibroids differ from patient to patient. Therapies, therefore, vary according to symptoms, the extent of the fibroids and the desire for the patient to have children.


Hysterectomy (removal of the womb) is often a treatment option for women who have completed their families. This option also prevents the formation of new fibroids (recurrence). 

Uterine-Sparing Therapies

Therapies that do not remove the womb can be an option if the symptoms and extent of the fibroids are not too severe, and most of these options preserve fertility;

  1. Intra-uterine device (IUD) – if heavy periods are the only symptom an IUD that releases hormones can be used to decrease bleeding. This option acts as a contraceptive (prevents pregnancy).
  2. Myomectomy (surgical removal of fibroids) – this option can improve a woman’s chance of becoming pregnant and is often the best treatment option.
  3. If the patient has completed their family, endometrial ablation (removes the inner lining (endometrium) of the womb) can be used to reduce heavy periods.

Hormone-Suppressive Therapy

Fibroids can grow in response to hormones. Therefore options that can suppress hormones can stop periods and reduce the size of fibroids.

Uterine Artery Embolism

Uterine artery embolization involves injecting small particles into the blood vessels that take blood to the womb, via the groin. The aim is to block the blood supply to the fibroids to relieve symptoms and reduce their size. This procedure is not very invasive and improves the quality of life of the patient. 

How do fibroids cause subfertility?

Fibroids are present in around 5-10% of women that have problems getting pregnant. Phil Druce from fertility prediction site OvulationCalendar.com says that “approximately 50% of women with fibroids that have infertility become pregnant after a myomectomy (having the fibroids removed)”. It is unknown exactly how fibroids could cause problems in becoming pregnant but several mechanisms have been proposed. Fibroids might cause a distortion of the uterus or cause the inner cavity of the uterus to enlarge. The fertilized egg may not be able to attach to the endometrium (inner lining of the womb) due to disturbed endometrial blood vessels or inflammation caused by fibroids that protrude out into the endometrium5.  It is also thought that fibroids could cause problems with the contractility of the uterus that affects the transport of the egg and sperm.

How can fibroids affect your pregnancy?

Fibroids in pregnancy are very commonly encountered, however, most do not cause any symptoms, but occasionally they can be linked with pressure symptoms such as an increased need to urinate or pain in 5-15% of patients. Your doctor will likely carefully monitor the size of your fibroids during pregnancy. It has been suggested that fibroids could cause some difficulties during labour due to insufficient uterine contractions. However, many women are able to achieve a normal vaginal delivery but some women may have to undergo a caesarean section. Increased size of the fibroids has been linked with an increased rate of caesarean. Research shows that the post-delivery outcome for mother and baby is usually good with little complication.

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