Most pregnancies with uterine fibroids are uneventful, and the effect on pregnancy and birth depends mainly on the size, number and location of the fibroids rather than on their mere presence. Small fibroids on the outer uterine wall rarely cause trouble at all. The ones that shape what happens are the growths that sit inside or distort the uterine cavity, sit low near the cervix, or grow large enough to compete with the placenta for blood supply.
This guide explains what clinicians look for during prenatal care, which changes are worth watching, and which symptoms mean you should call your prenatal care team rather than wait for the next visit. It is general information, not a diagnosis or a treatment plan for your pregnancy. Your obstetrician or midwife is the right person to apply any of it to your own situation.
Table of Contents
- Key risks at a glance
- How common are fibroids during pregnancy?
- How do most people find out?
- How do fibroids affect pregnancy?
- Can fibroids increase pregnancy complications?
- Abdominal and pelvic pain
- Placenta previa and placental abruption
- Fetal growth restriction
- Fetal position
- Preterm labor and preterm birth
- Postpartum hemorrhage
- How do fibroids affect labor and birth?
- What about delivery after a myomectomy?
- What are the signs that fibroids need medical attention?
- How are fibroids monitored during pregnancy?
- Do fibroids always require treatment during pregnancy?
- How can you talk with your prenatal care team?
- Frequently Asked Questions
- Do uterine fibroids make it harder to get pregnant?
- Can a fibroid cause miscarriage or affect fetal growth?
- Do fibroids mean I will have a cesarean birth?
- What symptoms should I contact my prenatal care team about?
- Will my healthcare provider need to check the fibroid during pregnancy?
- The first step for an expectant parent
Key risks at a glance
- Most common outcome: an uncomplicated pregnancy and birth. Reviews estimate roughly 10 to 30 percent of pregnancies with fibroids develop some complication, which means most do not.
- Most common complaint: localized pelvic pain, particularly in the second trimester, often from red degeneration as the fibroid outgrows its own blood supply.
- Biggest predictors of trouble: fibroids over 5 cm, fibroids inside or distorting the uterine cavity, and fibroids sitting low in the uterus near the cervix.
- Outcomes clinicians watch for: miscarriage, preterm labor and preterm birth, placenta previa, placental abruption, fetal growth restriction, breech or transverse position, cesarean delivery, and postpartum hemorrhage.
- Routine treatment during pregnancy: uncommon. Most fibroids are monitored rather than removed, because surgery during pregnancy carries its own risks.
How common are fibroids during pregnancy?
Uterine fibroids, also called leiomyomas or myomas, are benign smooth muscle growths that form in or on the wall of the uterus. They are extraordinarily common. Estimates suggest as many as 80 percent of women of reproductive age have them, and a review of the literature in the International Journal of Gynecology & Obstetrics puts prevalence in pregnancy somewhere between 1.6 and 10.7 percent.
That range is wide because it depends on how a study defines a fibroid and how carefully people are scanned. Estimating from symptom reports alone catches fewer than ultrasound screening does. Many people carry fibroids for years without knowing they are there.
How do most people find out?
The typical discovery is an ultrasound, either the dating scan in the first trimester or a later anatomy scan. A fibroid may also turn up incidentally during a fertility workup or a procedure such as hysteroscopy. Occasionally a fibroid that has been there for years becomes noticeable for the first time in pregnancy because the growing uterus and extra blood volume make it press on the bladder, bowel or pelvic floor.
Most people meet their care team already knowing the fibroid is there, and a growing share meet them as a routine note on a scan report. Either way, the useful questions are the same: how many, how big, and where exactly.
How do fibroids affect pregnancy?
Fibroids change pregnancy in only a few ways, and it helps to separate them. Some change the physical space the pregnancy occupies. Some compete for blood. Some interfere with how the uterus contracts. Some simply make a normally comfortable pregnancy uncomfortable.
Uterine fibroids affect pregnancy and birth mainly through location. A fibroid on the outside of the uterus has room to grow and rarely disturbs anything inside. A fibroid inside the uterine cavity changes the space available for implantation and for the fetus to sit in, and a fibroid low in the uterus can obstruct the birth canal or interfere with cervical dilation.
| Type | Where it sits | What it can affect |
|---|---|---|
| Subserosal | On the outer surface of the uterus | Usually little effect on pregnancy; occasionally causes pain if it twists or degenerates |
| Pedunculated | Attached by a stalk to the outside of the uterus | Twisting of the stalk is the main concern, and it can cause sudden sharp pain |
| Intramural | Within the uterine muscle wall | Can enlarge the uterus and, when large, compete with placental blood flow and reduce contraction strength |
| Submucosal | Protruding into the uterine cavity | Most likely of the four to distort the cavity, affect implantation and contribute to miscarriage risk |
Hormonal changes in pregnancy also explain why fibroids often grow in the first trimester, when hCG and estrogen peak. Growth mostly stabilizes after that, and many fibroids shrink in the months after birth. If you have been told a fibroid is growing, that is worth a growth scan, but it is not on its own a sign of a problem.
Can fibroids increase pregnancy complications?
Yes, and the list is worth knowing, but it should be read as a list of things clinicians monitor rather than things likely to happen to you. A recent systematic review and meta-analysis in BMC Women’s Health found that the presence of uterine fibroids is associated with increased odds of several adverse pregnancy and obstetric outcomes, and a meta-analysis in the Journal of Obstetrics and Gynaecology of Canada found a higher risk of threatened preterm labor and preterm premature rupture of membranes.
Abdominal and pelvic pain
This is the everyday reality of fibroids in pregnancy. As the uterus stretches and the fibroid adjusts, you may feel aching, pressure or cramping low in the abdomen or on one side. A specific event called red degeneration happens when a fibroid outgrows its own blood supply, and it typically brings sudden, one-sided pain in the second trimester. It is uncomfortable and alarming, and it usually settles with rest and time. What you can safely take for pain changes as the pregnancy advances, so that conversation belongs with your prenatal care team rather than being settled at home.
Placenta previa and placental abruption
Placenta previa means the placenta covers or sits very near the opening of the cervix. Placental abruption means the placenta separates from the uterine wall before birth. A low intramural or submucosal fibroid, or one that pushes the uterine cavity into an unusual shape, has less room for the placenta to implant normally, and that is the mechanism behind the association. Both conditions are monitored by ultrasound and warrant closer prenatal follow-up.
Fetal growth restriction
A large fibroid can divert blood flow away from the placenta, a mechanism sometimes described as the fibroid competing with the baby for resources. When that happens, growth scans become the main monitoring tool, and your provider may check the baby more often than the standard schedule.
Fetal position
Malpresentation means the baby is not head-down. A fibroid low in the uterus, or one that changes the shape of the uterine cavity, can crowd the baby and keep them from settling into a head-down position. Breech presentation and transverse lie are the two most common versions.
Preterm labor and preterm birth
Fibroids are associated with a higher rate of preterm birth in several meta-analyses, and the association is strongest when the fibroid is large. Uterine overdistension and altered contraction mechanics are the usual explanations.
Postpartum hemorrhage
After birth, the uterus contracts hard to compress the vessels that fed the placenta. A fibroid in the uterine muscle can soften that squeeze, and heavy bleeding after delivery is more common when fibroids are present. Knowing this in advance is what matters, because it means your team is watching for it and is already prepared to manage it.
How do fibroids affect labor and birth?
Many people with fibroids give birth vaginally, including people with fibroids over 5 cm. Whether a vaginal birth is likely comes down to position and size rather than to the diagnosis itself.
Three things influence labor. First, a fibroid low in the uterus or in the cervix can physically obstruct the birth canal or block cervical dilation. Second, a fibroid in the uterine muscle can weaken contractions, so labor may stall and progress slowly. Third, a baby who never settles head-down stays in a malpresent position and will not descend.
Any of those three can lead a provider to recommend a cesarean delivery. That recommendation is worth discussing carefully, especially when it is made early on the basis of a first-trimester scan. Ask what specifically would need to happen on the day, and what would change the plan.
What about delivery after a myomectomy?
Myomectomy is the surgical removal of fibroids while keeping the uterus. People with a prior myomectomy often worry that they must have labor induced or a cesarean. The reality is that many people labor vaginally after myomectomy. What your provider weighs is the depth and number of incisions in the uterine wall, whether the cavity was opened, and how the uterus behaved in previous pregnancies. The specific worry people raise is uterine rupture, where a weakened uterine wall tears during labor. The absolute risk is small, and the practice of scheduling a cesarean for every prior myomectomy is not universal, which is exactly why it belongs in a conversation with your own provider rather than in an article.
What are the signs that fibroids need medical attention?
Most fibroid discomfort is familiar and low-grade. Contact your prenatal care team promptly for any of the following, and use emergency services or urgent care for the last group.
- Pain that is severe, one-sided and sudden, especially if it comes with nausea or vomiting, since that pattern can indicate torsion or red degeneration.
- Heavy or persistent vaginal bleeding, or bleeding with pain.
- Contractions or cramping that are regular, painful and increasing in frequency before 37 weeks.
- Pelvic pressure, urinary urgency or difficulty passing urine that comes on suddenly rather than building slowly.
- A change in your baby’s usual pattern of movement, or movements that feel distinctly different.
- Dizziness, faintness, a racing heart, fever or chills, which point to something beyond a fibroid.
After delivery, treat any bleeding that soaks a pad in an hour, bleeding with clots, a rising heart rate, faintness or foul-smelling discharge as urgent rather than something to wait out.
How are fibroids monitored during pregnancy?
Monitoring depends on what your fibroid is doing. For a small, asymptomatic fibroid on the outer wall, monitoring may be as simple as standard prenatal visits and a note on your chart.
More commonly, your provider will want a growth scan at a specific interval rather than a scan at every visit. Knowing why you are having a repeat scan, and what number would actually change the plan, removes a lot of the anxiety that those appointments generate. Ask for the size to be compared with the prior measurement rather than quoted on its own, since a small difference is often just measurement noise.
Some clinicians also recommend a plan for pain, a discussion of birth mode closer to the third trimester, and a hospital team that knows about the fibroid before you arrive in labor. Keeping a short symptom note, with dates, what you did and what helped, makes those visits far more productive than trying to remember on the spot.
Do fibroids always require treatment during pregnancy?
No. Most fibroids are monitored rather than treated during pregnancy, and that is the standard approach. Surgery during pregnancy is generally reserved for situations where the fibroid is causing severe pain that does not settle, or where it is creating a risk that cannot be watched, such as suspected red degeneration with unremitting pain.
The reasoning is straightforward. Surgery brings anesthesia exposure, blood loss and a risk of complications, all during a pregnancy that was otherwise progressing normally. Most clinicians would rather manage pain and watch growth than add that risk. The exceptions tend to involve acute, severe symptoms rather than a fibroid that is merely large.
It is also worth knowing that fibroids frequently regress after birth, so a decision made now may not apply in six months. Some people are told to have fibroids removed before IVF or before trying to conceive, and that conversation is separate from pregnancy itself.
How can you talk with your prenatal care team?
The most useful prenatal visits for fibroid questions are short and specific. These are the questions that get clear answers.
- What is the exact location of my fibroids, and are any of them distorting the uterine cavity?
- Which measurements matter, and how often should they be repeated?
- Based on what you have seen, is a vaginal birth likely, and what would change that?
- What should I take for fibroid pain, and what should I avoid at this stage of pregnancy?
- What symptoms should send me to you rather than to the delivery unit, and which to the emergency department?
- Does my fibroid change your view of postpartum bleeding risk, and what should I watch for after birth?
- If I have had a myomectomy, how does that change my labor plan?
One practical note from people who have been through this: if you receive a C-section recommendation that another provider did not make, ask whether they have reviewed your ultrasound images rather than only the written report. That single question often unlocks a clearer conversation about whether the recommendation is about your specific anatomy or a general policy.
Frequently Asked Questions
Do uterine fibroids make it harder to get pregnant?
Sometimes, but many people conceive easily with fibroids in place. The ones most likely to interfere are submucosal fibroids that distort the uterine cavity, since they can make implantation difficult and are associated with a higher rate of miscarriage. Some fibroids can also compress or block a fallopian tube, and very large intramural fibroids can alter uterine anatomy. The effect is highly individual, so an honest answer comes from an ultrasound assessment of your own uterus rather than from a general statistic.
Can a fibroid cause miscarriage or affect fetal growth?
A fibroid can be associated with early pregnancy loss, particularly when it sits inside or distorts the uterine cavity, and with fetal growth restriction when a large fibroid competes with the placenta for blood flow. Neither is inevitable. Most pregnancies with fibroids continue without either problem, and clinicians usually reserve extra growth scans for fibroids over 5 cm or those in cavity-distorting positions. Ask your provider how your own fibroid is positioned before deciding how much monitoring you need.
Do fibroids mean I will have a cesarean birth?
No. Most people with fibroids give birth vaginally, including many with fibroids larger than 5 cm. A cesarean becomes more likely when a fibroid sits low in the uterus or on the cervix and blocks the birth canal, when it weakens contractions enough that labor stalls, or when the baby remains in a breech or transverse position. Those are individual findings, not a category. Ask what specifically would make a cesarean necessary on the day, and what your provider would need to see to change the plan.
What symptoms should I contact my prenatal care team about?
Contact your prenatal care team about severe or one-sided abdominal pain, sudden pelvic pressure, bleeding, contractions that become regular and painful, or a change in your baby’s usual movement. Seek urgent or emergency care for heavy bleeding, dizziness or fainting, fever, or a racing heart. Fibroid pain that builds slowly and settles with rest is usually not urgent, but pain that is sudden and sharp, or accompanied by nausea and vomiting, deserves a phone call the same day.
Will my healthcare provider need to check the fibroid during pregnancy?
It depends on size and location. A small fibroid on the outer uterine wall may need nothing beyond your routine prenatal visits and a note in your chart. Larger fibroids, fibroids inside the cavity, or ones causing symptoms usually mean a growth scan on a set interval. Ask what interval was chosen, why, and what change in measurement would actually alter your care, so a repeat scan feels purposeful rather than routine. Many fibroids also shrink after birth, so the plan is often revised at your postpartum visit.
The first step for an expectant parent
If you have just been told you have a fibroid, the single most useful thing to do at your next prenatal visit is to establish three facts: how many fibroids you have, how big they are, and exactly where they sit in relation to the uterine cavity and the cervix. Those three answers determine your monitoring schedule, your pain options and how your birth plan is likely to unfold.
Ask your provider what a vaginal birth would look like, what symptoms should reach them the same day, and whether anyone on your delivery team needs to know about the fibroid beforehand. With that information, most fibroid pregnancies become something you can manage calmly rather than plan around in fear.
This article is educational information and does not replace individualized obstetric advice. Decisions about monitoring, pain management and delivery belong with your obstetrician, midwife or other qualified healthcare professional.
