| "Vrouwen helpen hun ovulatie slimmer bij te houden" | 
Uterine fibroids (also called leiomyomas or myomas) are non-cancerous muscular growths that develop in or on the uterus. Affecting up to 80% of women by age 50, they are the most common pelvic tumor in women of reproductive age. Most fibroids are harmless, but submucosal or large intramural fibroids can alter the uterine cavity, impact fertility, and increase miscarriage risks. Treatment is not necessary for most asymptomatic fibroids, but may be considered when fibroids cause significant symptoms, affect fertility or pregnancy planning, or raise other clinical concerns.
Key Takeaways About Uterine Fibroids
- High prevalence: Fibroids are the most frequent gynecological condition, yet most women remain asymptomatic throughout their lives.
- Location dictates impact: Submucosal fibroids directly alter the endometrial lining, creating the greatest barrier to successful embryo implantation.
- Hormone-driven growth: Estrogen and progesterone fuel fibroid development during reproductive years, which then shrink naturally after menopause.
- Precision timing: Tracking your luteinizing hormone (LH) surge with the easy@Home and Premom fertility tracking system can help you time conception more confidently, even if fibroid bleeding disrupts cycle regularity.
Finding out you have uterine fibroids can bring up concerns when you are planning to conceive. According to Baird and colleagues in the American Journal of Obstetrics and Gynecology, uterine fibroids are the most common benign tumors of the female reproductive tract, affecting up to 80% of women by age 50. Fortunately, having fibroids rarely means you cannot build a family. Knowing how specific fibroid types behave helps you navigate your health decisions with confidence. Using the easy@Home & Premom fertility tracking system helps you track your LH surge so you can find your fertile window even if fibroids cause irregular bleeding.
What Are Uterine Fibroids?
Uterine fibroids are benign smooth muscle tumors that grow in or on the uterus. They vary from microscopic growths to large masses that expand the pelvic cavity.
What Happens When a Woman Has Fibroids?
When a woman has fibroids, her experience depends heavily on the size and location of the growths. Many experience no noticeable changes. Others develop heavy menstrual cycles, pelvic pressure, or abdominal swelling as the uterus expands.
How Serious Are Uterine Fibroids?
Fibroids are generally not dangerous. They require medical intervention only if severe menstrual bleeding causes anemia, or if their size causes severe pain or interferes with fertility.
Types of Uterine Fibroids: Locations and Classifications
How much a fibroid affects you depends on where it grows in the uterus. The main types of uterine fibroids and where they sit are compared below.
| Fibroid Type | Location | Prevalence | Primary Symptoms | Fertility Impact |
|---|---|---|---|---|
| Submucosal | Beneath the inner cavity lining | ~5–10% | Heavy periods, intermenstrual spotting | Highest: Directly disrupts implantation |
| Intramural | Within the muscular uterine wall | ~70% | Pelvic aching, heavy menstrual flow | Moderate: Impacts fertility if larger than 5 cm |
| Subserosal | On the outer surface of the uterus | ~20–25% | Frequent urination, lower back pressure | Low: Rarely affects cavity shape |
| Pedunculated | Attached to uterine wall by a stem | ~5% | Sharp localized pain if twisted | Low: Does not alter uterine lining |
| Cervical | Located within the cervical tissue | <1% | Pain during intercourse, discharge | Moderate: May block sperm movement |
Prevalence figures are general estimates; they vary between studies because many women have multiple fibroids and classification methods differ.
Intramural Fibroid: Clinical Significance
Because intramural fibroids expand within the muscle wall, they increase overall uterine volume. When they grow beyond 5 cm, they can alter the shape of the uterine cavity and weaken muscular contractions during menstruation.
Submucosal Fibroid: Fertility Challenges
Submucosal fibroids distort the inner endometrial lining. By occupying space in the cavity, they alter blood flow to the endometrium, making it difficult for a fertilized egg to attach securely.
Subserosal and Pedunculated Fibroids: Pressure Effects
Subserosal and pedunculated fibroids grow outward into the pelvis. Rather than affecting menstrual bleeding, they press against neighboring organs like the bladder and rectum, leading to pelvic discomfort and frequent urination.
Fibroids and Ovaries: Clarifying the Link
Fibroids grow exclusively from uterine muscle tissue, not ovarian tissue. Fibroids arise from uterine rather than ovarian tissue and generally do not directly interfere with ovarian reserve, egg quality, or ovulation.
Which Size of Fibroid Requires Medical Attention?
Fibroid size is a rough guide, not a verdict. Here is how doctors generally think about fibroids by size.
| Size Classification | Measurement | Typical Clinical Approach |
|---|---|---|
| Small | Under 4 cm | Routine monitoring during annual exams |
| Medium | 5–9 cm | Medical treatment or fertility evaluation |
| Large | 10 cm or greater | Surgical evaluation (myomectomy) recommended |
Fibroid size is only one factor in management. Treatment decisions are individualized based on symptoms, fibroid location and number, uterine cavity distortion, fertility goals, rate of growth, and overall health. Even large fibroids do not automatically require surgery.
What Causes Uterine Fibroids?
No single thing causes fibroids, but hormones, genetics, and family history all play a part.
Hormonal Drivers of Fibroid Growth
According to Stewart and colleagues in Nature Reviews Disease Primers, the main cause of fibroid growth is their sensitivity to the reproductive hormones estrogen and progesterone, which fuel the growth of the muscle and tissue that make up a fibroid during the reproductive years.
Genetics, Race, and Health Factors
Fibroid development involves genetics, ethnicity, and hormonal factors. Black women are approximately two to three times more likely to develop uterine fibroids than White women, tend to develop them at younger ages, and often experience larger and more numerous fibroids.
Do Birth Control Pills Cause Fibroids?
Birth control pills do not cause fibroids to form. Low-dose hormonal contraceptives are frequently prescribed by gynecologists to manage heavy menstrual bleeding caused by existing fibroids.
Uterine Fibroids Symptoms and Signs
Many women feel nothing at all. When fibroids do cause symptoms, these are the ones to know.
Signs of Fibroids and Pain Mechanisms
Signs of fibroids include heavy periods, pelvic fullness, and backaches. Fibroid pain occurs when expanding growths push against surrounding pelvic nerves or when a fibroid outgrows its blood supply, causing temporary tissue degeneration.
Heavy Menstrual Bleeding
Submucosal and intramural fibroids expand the surface area of the uterine lining and prevent the uterine muscle from contracting efficiently. This structural change leads to abnormally heavy or prolonged menstrual bleeding.
Abdominal Enlargement (“Fibroid Belly”)
When multiple or large fibroids develop, the entire uterus can swell to the size of a mid-term pregnancy. This creates visible lower abdominal protrusion, commonly called “fibroid belly.”
Complete Symptom Checklist
- Prolonged or heavy menstrual cycles
- Dull lower back or pelvic pressure
- Frequent urge to urinate
- Pain during sexual intercourse
- Abdominal bloating or swelling
Are Uterine Fibroids Cancerous?
Short answer: almost never. Here is what the word tumor does and does not mean when it comes to fibroids.
Understanding Malignancy Risk
Uterine fibroids are benign and do not transform into cancer. A rare cancer called uterine leiomyosarcoma can resemble a fibroid on imaging, but it is uncommon. According to ACOG, among women undergoing surgery for presumed fibroids, the risk of an unexpected leiomyosarcoma is estimated to range from approximately 1 in 770 to fewer than 1 in 10,000 cases.
Symptoms of Leiomyosarcoma
Key signs that require medical investigation include rapid growth of a uterine mass in postmenopausal women, severe unexpected pelvic pain, and bleeding after menopause.
Uterine Fibroids and Fertility: Can You Get Pregnant?
For most women, the answer is yes. What matters most is where a fibroid sits, not just that you have one.
Impact on Natural Conception
Most women with fibroids conceive naturally without difficulty. Fibroids are estimated to be the sole cause of infertility in only about 2–3% of infertile women. Submucosal fibroids are the type most likely to interfere with conception because they distort the uterine cavity and impair embryo implantation.
Location, Size, and Fertility Outcomes
- Outside the uterus (subserosal): These fibroids do not distort the cavity and rarely interfere with conception.
- Inside the wall (intramural): Fibroids under 5 cm typically do not hinder fertility, while larger ones may distort the cavity.
- Inside the cavity (submucosal): These fibroids impair implantation regardless of size and should be evaluated before conception.
Surgical Removal and Fertility Improvement
Removing cavity-distorting submucosal fibroids via hysteroscopic myomectomy is associated with improved pregnancy rates and a reduced risk of early pregnancy loss (Pritts et al., 2009).
Fibroids During Pregnancy: Risks and Delivery
Most women with fibroids have healthy pregnancies. A few situations are worth watching for.
How Fibroids Behave During Pregnancy
Elevated hormone levels during the first trimester can cause some fibroids to enlarge. Most remain stable or shrink during later trimesters without causing harm to the developing baby.
Pregnancy Risks and Delivery Options
Fibroids located near the inner lining slightly increase the risk of first-trimester miscarriage. Later in pregnancy, large fibroids can limit fetal movement, leading to breech positioning. If a fibroid blocks the cervical canal, a planned C-section becomes necessary. These situations are the exception, not the rule, and they are exactly what your prenatal scans are there to catch.
How Are Uterine Fibroids Diagnosed?
A professional clinical evaluation is required to confirm the presence and location of fibroids through these three standard steps:
- Pelvic examination: The gynecologist palpates the lower abdomen to check for uterine enlargement or irregular contours.
- Pelvic ultrasound: Transvaginal or abdominal ultrasound uses sound waves to image the uterus and measure fibroid dimensions.
- MRI scanning: Magnetic resonance imaging provides detailed cross-sectional views to map complex intramural or submucosal fibroids before surgery.
Uterine Fibroids Treatment and Management
Not every fibroid needs treatment. What you do depends on your symptoms and your plans for pregnancy.
Do Fibroids Go Away on Their Own?
Fibroids do not disappear on their own during your reproductive years. However, they naturally shrink after menopause when estrogen levels decrease.
Overview of Medical and Surgical Treatments
- Watchful waiting: Recommended for small fibroids that do not cause pain or bleeding.
- Medications: Hormonal therapies (like GnRH agonists or birth control) manage heavy bleeding and temporarily shrink growths.
- Myomectomy: Surgical removal of fibroids that preserves the uterus for future pregnancy.
- Uterine Fibroid Embolization (UFE): Minimally invasive procedure that blocks blood flow to shrink fibroids (typically for women not planning future pregnancy).
Track Your Fertile Window with Premom
If you have fibroids and are trying to conceive, tracking your ovulation cycle gives you clear next steps. Use the Premom app along with easy@Home ovulation test strips to log your daily LH levels. Logging your cycle data helps you time intercourse during your fertile window and gives your OB-GYN useful information.
Track your fertile window for free with Premom.
Key Terms Explained
- Uterine fibroids: Non-cancerous muscle tumors that grow within or on the walls of the uterus.
- Leiomyoma: The formal medical term for a benign uterine fibroid growth.
- Submucosal fibroid: A fibroid growing beneath the inner uterine lining that projects into the uterine cavity.
- Intramural fibroid: A fibroid embedded entirely within the muscular wall of the uterus.
- Myomectomy: A surgical procedure that removes fibroids while preserving the rest of the uterus.
Disclaimer
This content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with any questions you may have regarding a medical condition.
References
- Baird DD, Dunson DB, Hill MC, Cousins D, Schectman JM. High cumulative incidence of uterine leiomyoma in black and white women: ultrasound evidence. Am J Obstet Gynecol. 2003;188(1):100–107. doi:10.1067/mob.2003.99 https://pubmed.ncbi.nlm.nih.gov/12548202/
- Stewart EA, Laughlin-Tommaso SK, Catherino WH, Lalitkumar S, Gupta D, Vollenhoven B. Uterine fibroids. Nat Rev Dis Primers. 2016;2:16043. Published 2016 Jun 23. doi:10.1038/nrdp.2016.43 https://pubmed.ncbi.nlm.nih.gov/27335259/
- Uterine Morcellation for Presumed Leiomyomas: ACOG Committee Opinion, Number 822. Obstet Gynecol. 2021;137(3):e63–e74. doi:10.1097/AOG.0000000000004291 https://pubmed.ncbi.nlm.nih.gov/33595252/
- Pritts EA, Parker WH, Olive DL. Fibroids and infertility: an updated systematic review of the evidence. Fertil Steril. 2009;91(4):1215–1223. doi:10.1016/j.fertnstert.2008.01.051 https://pubmed.ncbi.nlm.nih.gov/18339376/
- American Society for Reproductive Medicine. Removal of myomas in asymptomatic patients to improve fertility and/or reduce miscarriage rate: a guideline. Fertil Steril. 2017;108(3):416–425. doi:10.1016/j.fertnstert.2017.06.038 https://www.sciencedirect.com/science/article/pii/S0015028217304934
