Fibroids can shrink after a miscarriage, but the odds are lower than after a full-term pregnancy. In a study of 44 women with fibroids who experienced miscarriage, about 35% saw their total fibroid volume drop by more than half within three to six months. However, 25% actually saw their fibroids grow by more than half in that same window, and the remaining 40% had minimal change in size.
Why Fibroids Sometimes Shrink After Pregnancy Loss
Fibroids depend heavily on estrogen and progesterone to grow. During pregnancy, levels of both hormones surge, and fibroids often enlarge in response. After a miscarriage, those hormone levels drop, removing a key growth signal. This hormonal shift is the main reason some fibroids regress afterward.
The timing of the miscarriage matters. Later miscarriages are associated with greater fibroid shrinkage, likely because the body experiences a more dramatic hormonal shift. A loss at 14 weeks involves a much steeper decline in pregnancy hormones than one at 6 weeks. In very early losses, the hormonal change may be too small to meaningfully affect fibroid size.
How This Compares to Shrinkage After a Full-Term Birth
Fibroids are far more likely to shrink after carrying a pregnancy to term than after a miscarriage. Women who had miscarriages were roughly 80% less likely to experience significant fibroid regression compared to women who delivered live births. That’s a substantial difference, and it comes down to the same principle: a full-term pregnancy involves nine months of massive hormonal and blood-flow changes to the uterus, followed by a dramatic reversal. A miscarriage, especially an early one, simply doesn’t create the same degree of physiological shift.
What Can Happen Instead of Shrinkage
Since a quarter of women in the study saw their fibroids actually grow after miscarriage, it’s worth understanding why. Fibroids that enlarged during even a short pregnancy may not fully return to their pre-pregnancy size, particularly if the loss occurred early and hormone levels didn’t swing significantly. Individual variation also plays a role. Factors like age, the number and location of fibroids, and underlying blood supply to the uterus all influence whether a given fibroid shrinks, stays the same, or continues growing.
In rarer cases, fibroids can undergo a process called red degeneration during or shortly after pregnancy. This happens when a fibroid outgrows its blood supply and the tissue inside begins to break down. Symptoms include severe abdominal pain, tenderness over the lower abdomen, mild fever, nausea, and vomiting. On imaging, a degenerating fibroid looks distinctly different from a healthy one: more uneven in texture, sometimes with fluid-filled areas, and with reduced blood flow visible on ultrasound. Red degeneration is painful but typically resolves on its own with supportive care. It does not mean the fibroid is simply “shrinking” in a healthy way.
Monitoring Fibroids After Miscarriage
There are no widely standardized guidelines telling doctors exactly when to recheck fibroid size after a miscarriage. In research settings, follow-up ultrasounds have been performed three to six months after the loss, which gives enough time for post-pregnancy hormonal changes to stabilize and for any fibroid regression to become measurable. If you have known fibroids and have experienced a miscarriage, an ultrasound in that timeframe can establish whether your fibroids have changed and help guide next steps for treatment or future pregnancy planning.
After your menstrual cycles return to normal, the hormonal environment that supports fibroid growth is back in place. Any shrinkage that occurred may not be permanent, and fibroids can resume growing over subsequent months and years. This is true whether the shrinkage followed a miscarriage, a full-term delivery, or menopause-related hormone shifts that are later reversed with hormone therapy. Ongoing monitoring is the most practical way to track changes over time.
Fibroids, Miscarriage, and Future Pregnancies
If you’re asking this question because you’re planning to try again, the relationship between fibroids and miscarriage risk is worth understanding. Professional organizations like the American Society of Reproductive Medicine have noted that surgical removal of fibroids before conception can reduce miscarriage risk by as much as 50% in certain cases, particularly when fibroids distort the uterine cavity. Not all fibroids carry equal risk. Those growing into the uterine lining (submucosal fibroids) are most strongly linked to pregnancy complications, while fibroids on the outer surface of the uterus may have little impact.
Whether to treat fibroids before another pregnancy depends on their size, number, and location. A fibroid that shrank modestly after a miscarriage but still distorts the uterine cavity presents a different picture than a small one embedded in the muscle wall. Imaging after the miscarriage gives you and your doctor the information needed to make that decision with clarity rather than guesswork.