Being diagnosed with fibroids during pregnancy is concerning — but for the majority of women, fibroids do not significantly affect pregnancy outcomes. Understanding the actual risks, which depend heavily on fibroid size and location, helps you navigate this situation with accurate information rather than generalised anxiety.
How Common Is This?
Fibroids are present in 2–12% of pregnancies, though the true figure is likely higher as many are never identified. Many women discover fibroids for the first time during a routine pregnancy ultrasound. In the majority of these cases, no specific intervention is needed — just monitoring.
How Pregnancy Affects Fibroids
Pregnancy hormones — particularly estrogen and progesterone — can stimulate fibroid growth, particularly in the first trimester. Studies show that approximately 50–60% of fibroids do not change significantly in size during pregnancy. Around 22–32% grow — usually in the first trimester — and some actually shrink.
Predicting which fibroids will grow is difficult. Regular ultrasound monitoring throughout pregnancy is the most practical approach.
Potential Complications By Fibroid Type
Risk varies significantly by fibroid location. Submucosal fibroids (inside the uterine cavity) carry the highest risk, including increased miscarriage risk and preterm labour. Intramural fibroids (within the wall) present intermediate risk when large or cavity-distorting. Subserosal fibroids (on the outer wall) carry the lowest obstetric risk.
Possible complications include higher rates of caesarean delivery, placenta previa, placental abruption, preterm labour, and postpartum haemorrhage. These are elevated risks — not certainties. Many women with fibroids in all three locations have entirely uncomplicated pregnancies.
Fibroid Degeneration in Pregnancy
When a fibroid outgrows its blood supply during pregnancy, it undergoes degeneration — a painful process that typically causes localised pelvic pain, low-grade fever, and occasionally nausea. This is managed with rest and pain relief (paracetamol is generally considered safe; NSAIDs are typically avoided after the first trimester). It is uncomfortable but does not usually threaten the pregnancy.
What To Discuss With Your Doctor
Know the size, number, and location of your fibroids before or early in pregnancy. Ask specifically about your fibroid type and what monitoring schedule is appropriate. Understand what symptoms to watch for and when to seek urgent evaluation. See our guide on fibroids and fertility if you are planning pregnancy.
After Delivery
Many fibroids shrink significantly postpartum as hormone levels change. Some women find their symptoms are reduced after completing their family. Others choose to address fibroids through treatment after delivery. The postpartum period is a reasonable time to reassess your situation with current imaging and consider your options.
