How Fast Do Fibroids Grow? Signs It's Time to See a Doctor

When a doctor says your uterine fibroids are small enough to watch, it is easy to hear that and think "nothing to worry about". Yet a watch-and-wait approach only works when you know what you are watching for. Most women leave that conversation without a clear answer on what changes should prompt them to return.

Knowing what causes fibroids to grow, how growth is monitored, and when to speak to your doctor can help you feel more prepared and informed throughout your care.

What are uterine fibroids?

Uterine fibroids are benign (non-cancerous) growths that develop in or on the uterus. They are made of smooth muscle and fibrous tissue, and they are more common than many women realise, particularly during their 30s and 40s.

Fibroids vary enormously in size. Some are small and cause no problems at all, while others are large enough to press on nearby organs or change the shape of the uterus. Many women live with fibroids without ever knowing they have them.

When symptoms do appear, they can include:

• Heavy or prolonged periods

• Pelvic pressure or discomfort

• Frequent urination

• Constipation

• Back or leg pain

Not everyone will experience all of these, and the severity varies greatly. The impact on your daily life is what guides whether treatment is needed.

Fibroid size categories

Fibroids are generally grouped by size to help guide monitoring and treatment decisions. 

As a general guide:

• Small fibroids are usually less than 3 cm and often cause no symptoms

• Medium fibroids are usually 3 to 6 cm and may cause noticeable symptoms

• Large fibroids are usually more than 6 cm and may be more likely to affect nearby organs or daily life

These size ranges are only a general guide. A small fibroid inside or close to the uterine cavity may cause heavier bleeding, while a larger fibroid on the outer surface of the uterus may mainly cause pressure symptoms or no symptoms at all. Your doctor will consider both size and position when assessing your fibroids.

How fast do fibroids grow?

Fibroids do not follow a single predictable path. Some grow steadily, others stay still for long stretches, and some go through periods of faster change. Knowing the common patterns can help you make sense of what your doctor tells you at your monitoring appointments.

Slow, gradual growth

This is the most common growth pattern. Many fibroids increase in size very gradually over years, with long periods where they stay roughly the same. They often slow down or stop growing around menopause, when oestrogen levels naturally fall.

Periods of faster growth

Occasionally, fibroids may grow more quickly over several months. This can happen during hormonal changes. Fibroids can also go through a process called 'fibroid degeneration', where they break down internally. This may change how the fibroid appears on imaging, though it does not always mean the fibroid has grown larger.

Fibroid degeneration can sometimes cause sudden or localised pelvic pain, especially during pregnancy or when a fibroid outgrows its blood supply. If pain is severe, persistent, or accompanied by fever or heavy bleeding, seek medical advice promptly. 

Faster fibroid growth is not always a cause for concern, but it does warrant closer monitoring by your doctor.

What makes fibroids grow faster?

Several factors can influence how quickly your fibroids grow. Some of these are things you have no control over, such as your genetics, while others relate to broader aspects of your health and lifestyle.

Hormones and age

Because fibroids respond to these hormones, they tend to be most active during your reproductive years and less so as those levels naturally begin to shift. The transition period leading up to menopause (known as perimenopause) can bring hormonal changes that affect fibroid behaviour in less predictable ways.

Pregnancy

Pregnancy is one of the times when fibroids are most likely to change in size due to rising hormone levels and increased blood flow to the uterus. 

Depending on the size and location of your fibroids, there are a few things your doctor will monitor:

• A possible increased risk of miscarriage, particularly if fibroids distort the uterine cavity or affect implantation 

• Changes in your baby's position as the pregnancy progresses

• Whether a caesarean section may be recommended depending on the position of your fibroids and your baby

In some cases, your pregnancy may be classified as high risk, but many women with fibroids go on to have straightforward pregnancies.

After the birth, many fibroids that grew during pregnancy shrink back, though your doctor will reassess and advise on any further care needed.

Lifestyle

Certain factors may play a role in fibroid growth, though they are not direct causes. 

These include:

• Higher body weight, which can raise oestrogen levels in the body

• Persistent inflammation, which may affect how your body responds to hormonal changes

• Diet patterns that affect hormone balance

Looking after your general health cannot eliminate fibroids or guarantee slower growth, but it can support overall wellbeing and may help manage factors linked to hormonal health.

Fibroid growth can be influenced by hormones, pregnancy, and wider health factors, which is why regular monitoring can be helpful. Request an appointment with Thomson Medical to discuss whether any follow-up scans or treatment options may be appropriate for you.

When do fibroids stop growing?

For many women, fibroids begin to slow down as they approach menopause. Once the body's oestrogen levels fall significantly after menopause, most fibroids stop growing and some even shrink over time. 

Hormone replacement therapy (HRT) after menopause may cause some fibroids to remain active. Your doctor can help you understand how this might affect your individual situation.

That said, fibroids do not always follow this pattern neatly. Some women find that their fibroids continue to cause symptoms even after menopause, particularly if they remain large. A small number of fibroids may continue to grow after menopause, which is something your doctor will want to investigate more carefully.

If you have had no symptoms for a long time and are postmenopausal, your doctor may still recommend routine monitoring appointments to make sure everything remains stable.

Signs that your fibroids may be growing

Your body often gives you signals before a scan confirms any change in size. Paying attention to how you feel from month to month is a useful way to track what is going on.

You might notice:

• A fuller or heavier feeling in your lower abdomen

• Heavy menstrual bleeding or longer bleeds

• Needing to urinate more often

• A feeling of pressure or discomfort in the pelvis

• New or worsening back or leg pain

These changes are worth raising with your doctor. An imaging scan is usually the only way to confirm whether your fibroids have actually changed in size. If something feels different, speak to your doctor promptly.

Can fast-growing fibroids be a sign of cancer?

This is a concern many women have after a fibroid diagnosis. Fast growth on its own is not a sign of cancer. The vast majority of fibroids, regardless of how quickly they grow, are not cancerous.

There is a cancer called uterine leiomyosarcoma that can look similar to a fibroid on imaging. It is uncommon, but your doctor will take it seriously if there are any concerning features.

These may include:

• Rapid enlargement after menopause

• Severe or unexplained pelvic pain

• Unusual vaginal bleeding patterns

Fibroid growth alone does not always mean treatment is needed. Your doctor will consider whether the fibroid is causing symptoms, affecting nearby organs, changing after menopause, or affecting pregnancy plans. 

If your doctor has any concerns, they will arrange appropriate imaging and assessment to get a clearer picture. 

How doctors monitor fibroids

If your fibroids are stable and your symptoms are manageable, your doctor will likely recommend monitoring rather than immediate treatment. This approach gives you and your doctor a clear, ongoing picture of how your fibroids are behaving over time.

Monitoring tools may include:

• Pelvic exam to check the uterus

• Pelvic ultrasound for tracking fibroid size

• MRI scan used when more detailed imaging is needed

Monitoring appointments are typically arranged every six to twelve months. However, you may need earlier follow-up if symptoms change, fibroids are enlarging, pregnancy is planned, or growth occurs after menopause. 

If your fibroids are stable and symptoms are not affecting your daily life, keeping those appointments may be all that is needed.

What are your options if fibroids are growing?

If your fibroids are growing and affecting your quality of life, it may be time to consider the options available to you. Each type of treatment has potential benefits, limitations, risks, side effects, and recovery considerations. Your doctor will discuss these with you before recommending an approach. 

Options may include:

• Medications:

  • Hormonal medication helps manage symptoms such as heavy bleeding or pelvic pain.

  • Pain relief may also help ease discomfort, and some hormonal treatments, such as contraceptive pills, may offer additional symptom control

• GnRH medicines:

  • May help shrink fibroids and reduce bleeding in suitable patients

  • Are sometimes used before surgery or as part of a broader treatment plan

  • May have side effects, so your doctor will discuss whether they are appropriate for you

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• Uterine artery embolisation (UAE):

  • A minimally invasive procedure that blocks the blood supply to your fibroids, causing them to shrink gradually over time

• Myomectomy:

  • Removes fibroids while keeping your uterus intact. This is often considered when preserving your fertility is important.

• Hysterectomy:

  • Removes the uterus entirely. Usually considered when other treatments have not provided enough relief and a future pregnancy is not planned.

Treatment is not the same for every woman, and the most suitable option depends on your symptoms, your age, and your plans for the future. Your doctor can help you understand your options and decide on the approach that best suits your situation.

When should you speak to your doctor?

Most fibroids, even if they grow, do not lead to serious complications. There are, however, some situations where it is important not to wait for your next scheduled appointment.

You should speak to your doctor promptly if:

• Your fibroid symptoms are getting significantly worse

• You are experiencing severely painful periods or new pelvic pain

• Heavy periods are leaving you feeling exhausted or breathless, which may suggest anaemia

• A fibroid appears to be growing after menopause

Postmenopausal growth in particular needs careful evaluation, as fibroids should naturally become less active once oestrogen levels fall. If fibroids continue to grow after menopause, your doctor will want to investigate further.

If your fibroid symptoms are becoming more severe or affecting your daily life, request an appointment with Thomson Medical for an assessment of your fibroid size, location, and possible treatment options.

FAQ

How fast do fibroids grow?

Fibroid growth rates vary widely. Some fibroids grow very slowly over several years, while others may enlarge by several centimetres within a year, particularly during pregnancy or periods of hormonal change.

Do fibroids grow faster during pregnancy?

Some fibroids may increase in size during pregnancy, especially earlier in pregnancy, while others remain stable or shrink. Your doctor may recommend monitoring depending on their size, location, and whether they are causing symptoms.

Does birth control affect fibroid growth?

Hormonal birth control can help regulate menstrual bleeding and reduce symptoms, but it does not usually shrink fibroids significantly. Its effects on fibroid growth may vary from woman to woman.

Can fibroids stop growing on their own?

Yes, fibroid growth often slows or stops as women approach menopause because oestrogen and progesterone levels decline. Some fibroids may also shrink after menopause.

Should fast-growing fibroids be removed?

Not necessarily. The decision to remove fibroids depends on factors such as symptoms, fibroid size, age, fertility goals, and whether menopause has occurred. Rapid growth should be evaluated by a doctor, but it does not automatically mean surgery is required.

How often should fibroids be monitored?

Stable fibroids without symptoms are often monitored every 6 to 12 months. If fibroids are enlarging or causing symptoms, more frequent monitoring with ultrasound or MRI may be recommended.

Can a fibroid grow in 6 months?

Yes, fibroids can grow within 6 months. Some fibroids enlarge slowly over years, while others may increase in size more noticeably over a shorter period, especially during pregnancy, hormonal changes, or reproductive years. Growth rates vary, which is why regular monitoring with ultrasound or MRI may be recommended if symptoms change or the fibroid appears to be enlarging.

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice based on your unique situations, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.