There is no safe, proven way to actively shrink fibroids while you are pregnant. The standard treatments used outside of pregnancy, such as hormonal therapies and procedures like uterine artery embolization, are not options during pregnancy because they can harm the fetus. The good news: over 70% of women see their fibroids shrink by more than half on their own within a few months after delivery. During pregnancy itself, the goal shifts from shrinking fibroids to managing symptoms and monitoring for complications.
Why Fibroids Can’t Be Shrunk During Pregnancy
Outside of pregnancy, fibroids are typically treated with medications that alter hormone levels or with minimally invasive procedures that cut off blood supply to the fibroid. None of these are safe for a developing baby. The rising estrogen and progesterone levels that sustain pregnancy also tend to fuel fibroid growth, which means the hormonal environment itself is working against shrinkage.
Surgery to remove fibroids during pregnancy (myomectomy) is reserved for rare, extreme situations. It’s not a shrinkage strategy. In a prospective study of pregnant women who underwent myomectomy, 14.3% experienced miscarriage during the procedure, and about 32% developed threatened preterm birth afterward. Surgeons consider it only when pain doesn’t respond to medication for more than 72 hours, when a fibroid is compressing the baby or pelvic organs, or when there’s a high risk of serious complications like restricted fetal growth.
What Happens to Fibroids During Pregnancy
Fibroids are unpredictable in pregnancy. Some grow, some stay the same, and some undergo a process called degeneration, where the fibroid outgrows its blood supply and the tissue inside begins to break down. This can cause sudden, sharp abdominal pain, most commonly in the second and third trimesters, and is more likely with fibroids larger than 5 cm. The pain can be severe enough to mimic appendicitis or other emergencies, but the condition is typically self-limiting. Diagnosis is confirmed with ultrasound or MRI, and treatment is conservative: rest, fluids, and pain relief. The prognosis for both mother and baby is usually good.
Managing Fibroid Pain Safely
Pain is the most common fibroid-related complication during pregnancy. The standard approach is conservative: bed rest, staying well hydrated, and using pregnancy-safe pain relievers like acetaminophen. Anti-inflammatory pain medications need to be used cautiously, particularly in the third trimester. Prolonged use (more than 48 hours) at that stage has been linked to serious fetal complications, including premature closure of a critical blood vessel in the baby’s heart and low amniotic fluid levels.
In rare cases where pain is severe and doesn’t respond to basic pain relief, stronger options like epidural pain management may be considered. The vast majority of women, though, find that conservative measures are enough to get through the painful episodes.
Complications to Watch For
Most pregnancies with fibroids proceed without major problems, but larger fibroids (over 5 cm) and those located near the placenta or in the lower part of the uterus carry higher risks. Complications associated with large fibroids include preterm labor, placental abruption (where the placenta separates from the uterine wall early), malpresentation (the baby settling into a breech or other non-head-down position), and difficult labor.
In one study of women with large fibroids, preterm labor occurred in about 7% of cases, and malpresentation in about 5%. These rates were actually lower than some earlier estimates, which ranged as high as 26% for preterm labor and 13% for malpresentation. The wide range reflects how much fibroid size, number, and location matter. A single small fibroid on the outer wall of the uterus poses far less risk than multiple large fibroids distorting the uterine cavity.
Your provider will likely monitor your fibroids with periodic ultrasounds throughout pregnancy, paying attention to their size, growth rate, and proximity to the placenta and cervix.
How Fibroids Affect Delivery
Having fibroids does not automatically mean you need a cesarean section. Many women with fibroids deliver vaginally without complications. A C-section becomes more likely when a fibroid is positioned in the lower uterine segment or near the cervix, where it can physically block the baby’s path. It’s also more common when fibroids contribute to malpresentation or when labor fails to progress normally.
In cases where a fibroid is in the lower uterine segment and a C-section is already being performed, surgeons sometimes remove the fibroid at the same time. This isn’t routine, however, because removing fibroids from a pregnant uterus increases the risk of heavy bleeding. The decision depends on the fibroid’s specific location and whether it’s obstructing the surgical delivery itself.
Vitamin D and Fibroid Growth
One area of growing interest is the relationship between vitamin D levels and fibroid behavior. A large prospective study tracking women over several years found that having adequate vitamin D levels (at least 20 ng/ml in the blood) was associated with roughly a 10% reduction in fibroid growth rate compared to women with lower levels. Women with levels above 30 ng/ml showed an even more promising pattern: a 22% lower chance of developing new fibroids and a 32% higher chance of existing fibroids disappearing entirely.
These findings come from a general population study, not one conducted specifically during pregnancy. But vitamin D supplementation is considered safe during pregnancy and is already recommended for fetal bone development. If your levels are low, bringing them up to an adequate range may offer a modest benefit for fibroid management alongside its other well-established benefits. Your prenatal bloodwork can reveal whether you’re deficient.
Natural Shrinkage After Delivery
The most significant fibroid shrinkage happens on its own after you give birth. Once pregnancy hormones drop, fibroids lose a major growth stimulus. A study published in the American Journal of Obstetrics and Gynecology found that 72% of women experienced greater than 50% reduction in total fibroid volume within three to six months postpartum. That’s a dramatic decrease that happens without any intervention.
This postpartum regression is the reason many providers recommend a “watch and wait” approach during pregnancy. The fibroids that seem alarming at 30 weeks may be half their size or smaller by the time your baby is six months old. For women whose fibroids do remain large or symptomatic after delivery, the full range of treatment options, including medication, minimally invasive procedures, and surgery, becomes available again once pregnancy and breastfeeding considerations are resolved.