How Can Uterine Fibroids Affect Your Pregnancy?

    Updated 16 February 2022 |
    Published 27 December 2018
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    Reviewed by Dr. Anna Klepchukova, Intensive care medicine specialist, chief medical officer, Flo Health Inc., UK
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    Find out what are uterine fibroids, the link between uterine fibroids and pregnancy, and how you can best treat them.

    What are uterine fibroids?

    Uterine fibroids are benign muscular growths that can develop inside or outside the uterus, usually in women in their childbearing years. They are also called leiomyomas or myomas.

    Fibroids are almost always benign in nature and are extremely common – almost 40 to 60% women get fibroids by the age of 35, and 60-80% by the time they turn 50. They can be found as a single growth or in clusters. The size of a single fibroid can vary greatly – from 1 mm (a coin) to 8 inches in diameter in size – for perspective, a uterus is usually 4 inches in diameter, so a fibroid that big can distend your belly and cause discomfort.

    How uterine fibroids are detected?

    Most fibroids are detected in a routine pelvic examination. However, this usually happens when their size is large enough to be palpated during bimanual examination, and smaller fibroids go undetected for long periods of time, especially if they cause no symptoms.

    An ultrasound, MRI, hysteroscopy and saline-infused sonography can be taken as further tests to confirm their presence.

    Types of uterine fibroids

    Fibroids are classified based on the area of the uterus they grow in, and it’s possible to have more than one type at the same time:

    • Intramural fibroids: The most commonly found type of fibroids, these fibroids grow within the walls of the uterus. The more they grow in size, the more they can stretch the uterus.
    • Subserosal fibroids: These fibroids grow outside the uterus and can put outward pressure on the surrounding organs, as they grow in size.
    • Submucosal fibroids: These are the rarest form and grow in the submucosa layer – the layer just underneath the uterine lining, and can bulge inwards into the uterus, and cause cramping and bleeding.
    • Depending on how deep the fibroid lies in the uterine wall they are classified by FIGO as type 1 and type 2.
    • Pedunculated fibroids: Some subserosal and submucosal fibroids grow on slim muscular stems, called stalks, that support the fibroids. In that case, they’re known as pedunculated fibroids.  Submucosal pedunculated fibroids are classified by FIGO as type 0 fibroid.

    What causes uterine fibroids?

    While medical research has not yet found clear answers to what causes uterine fibroids, but the following factors have been shown to play a role in their development:

    • Hormonal factors: Female reproductive hormones, estrogen and progesterone, are responsible for the growth and development of the uterine lining every month. These hormones have been shown to promote the growth of fibroids - the cells make up fibroids appear to be stimulated when exposed to these hormones. This is also why the chances of developing uterine fibroids after menopause are very low, due to the lack of reproductive hormones.
    • Genetic factors: It has been observed that having a family member or more with fibroids increase one’s probability of developing fibroids - suggesting a hereditary link.
    • Other risk factors: Studies have observed the occurrence of uterine fibroids to be higher in women that are of African-American descent, and obesity has also been observed to play a role in developing fibroids.

    Symptoms of uterine fibroids

    Most women with fibroids experience no symptoms and may not even realize they have fibroids. However, about 30% of fibroids are symptomatic.

    The following are the most common symptoms found:

    Fibroids and fertility

    While many women with fibroids don’t experience fertility issues, the location and size of certain fibroids may cause fertility complications in some women in the following ways:

    • A large fibroid that changes the shape and size of the uterus can interfere with the movement of the sperm and/or the fertilized egg and prevent implantation.
    • Fibroids can cause fallopian tubes to be blocked, preventing the egg from reaching the uterus.
    • Submucosal fibroids have been observed to be linked to infertility as they reduce the chances of implantation of the fertilized egg to the uterine lining.

    Uterine fibroids and pregnancy

    Although many women have a smooth pregnancy despite of fibroids, around 10 - 30% of women with fibroids develop pregnancy related complications. Let’s take a look at their possible impact on pregnancy alongside its various stages:

     Early pregnancy
    • Miscarriage: Research shows twice the risk of spontaneous miscarriage (14%) in women with fibroids, compared to those without fibroids (7.6%). Also, having multiple fibroids rather than a single growth increases this risk further. Women with intramural or submucosal fibroids have also been observed to be more likely to experience early miscarriage.
    • Bleeding: Studies have shown a greater risk of bleeding (60%) in early pregnancy if the placenta is implanted close to the fibroid, compared to when there is no contact between the two (9%).
    Late pregnancy
    • Pre-term labor: Women with uterine fibroids during pregnancy are almost twice as likely to undergo premature delivery, compared to those without fibroids.
    During labor
    • IVF Success rate: Studies have linked having intramural fibroids with reduced success rates of live births (the rate of successful births, after adjusting for miscarriages and stillbirths) in IVF (In-vitro fertilization) pregnancies.
    • C-Section: Having fibroids has been linked to an almost four fold increased chance of having a cesarean section delivery, compared to women without fibroids.

    How pregnancy affects fibroids

    Even though a majority of fibroids don’t change in size during pregnancy, around one-third of them may grow during the first trimester. This could be because pregnancy causes a rapid rise in the estrogen levels of the body, the hormone that has been observed to stimulate growth of fibroids.

    How to treat uterine fibroids during pregnancy?

    For some women, fibroids can be a constant source of acute and chronic pain during pregnancy. Since surgical treatments should be avoided during pregnancy, the following tips and methods can help bring relief and manage symptoms:

    • Rest and hydration: Bed rest and staying well hydrated can help bring relief from fibroid pain.  
    • Green tea: Adding green tea to your diet has shown promise as one of the natural remedies for uterine fibroids, not only reducing the size of fibroids, but also the severity of symptoms experienced. Studies have shown that the presence of EGCG, in green tea, leads to a shrinkage in the size of the fibroid, and also reduce blood loss, without any side effects.
    • Fiber rich diet: Eating a diet rich in fruits, vegetables and whole grains helps in preventing fibroid symptoms from worsening. Avoid refined flour, alcohol, and sugary or overly salty foods, as they may aggravate the symptoms.
    • Anti-inflammatory drugs: While over the counter non-steroidal painkillers can be used to manage fibroid pain, make sure to consult your doctor before using them, as they can have an adverse effect on the pregnancy in the third trimester.

    How are fibroids treated before pregnancy to improve fertility?

    There different options like hormonal pills, hormonal IUD or surgery to treat fibroids. Since each treatment has its own pros and cons, it is highly advised to explore the impact of all the following options for treatment of uterine fibroids in detail with your doctor before deciding upon the one that is right for you.

    Here are the options of the uterine fibroids surgical treatment.


    This is a surgical procedure in which symptom causing fibroids are removed, while keeping the uterus intact. This method has been known to have a low complication rate and is an option for women that would like to get pregnant in the future. Myomectomy is more effective for preserving fertility if compared to UAE

    Uterine artery embolization

    This minimally invasive procedure is an option for women who want to avoid surgery and are suffering from heavy bleeding due to fibroids. In this procedure, the doctor inserts a slim, flexible tube that injects particle to cut off the blood supply to the fibroids, eventually leading them to starve, shrink and die. However, in some cases, this procedure could lead to fertility complications in the future.

    Hysteroscopic myomectomy

    This is a procedure during which a submucosal fibroid (type 0, 1 and 2) up to 5 cm. (2 inches) in diameter is removed through the cervix by using an instrument called a resectoscope.

    4 most common questions about uterine fibroids

    Aside from the details we have already explored on the topic, here are some of the most common questions we get about uterine fibroids, and the answers to each of them:

    What do uterine fibroids look like?

    Fibroids typically look well-defined, solid masses that are firm and usually round in shape. Smaller sized fibroids may not cause any change in your outward appearance, whereas some large fibroids can distend your midsection and almost make you look pregnant.

    What causes fibroids to grow?

    While medical research is yet to pinpoint the exact factors that cause fibroids to grow, they have been seen to grow when the reproductive hormone levels – estrogen and progesterone – are high.

    This usually happens during pregnancy, when the levels of both estrogen and progesterone rise rapidly. Anti-hormone medications have been observed to shrink the size of fibroids, and so has the onset of menopause.

    Are uterine fibroids cancerous?

    Uterine fibroids are almost always benign growths (non-cancerous) and are rarely ever cancerous (a one in thousand occurrence). Having benign fibroids does not increase your risk of developing a cancerous fibroid or any other cancer of the uterus.

    What causes uterine fibroids to grow after menopause?

    Since menopause is marked by a dramatic decline in a woman’s estrogen levels, this usually means that any fibroids shrink in size after menopause and stop growing.

    However, if you are taking hormone replacement therapy (HRT), then your fibroid-related symptoms and size will persist (since fibroids are stimulated by estrogen). Keep in mind that in the absence of HRT, your fibroids should not be growing in size after menopause. In case you still observe a growth in size, do consult your doctor for an examination.


    Despite of their widespread occurrence, there is much research yet to be done to fully understand the causes, prevention and treatment of uterine fibroids.

    While most women with fibroids do not face any adverse symptoms or pregnancy complications, there are still cases where the size and location of fibroids can cause fertility and pregnancy issues.

    If you are detected with uterine fibroids, it is advised to discuss it at length with your doctor, and decide on whether your case needs treatment, and if yes, which option works best for you, depending on your specific case and any future pregnancy plans.

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    History of updates

    Current version (16 February 2022)

    Reviewed by Dr. Anna Klepchukova, Intensive care medicine specialist, chief medical officer, Flo Health Inc., UK

    Published (27 December 2018)

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