Uterine fibroids are the most common benign (noncancerous) gynecologic tumors, and are found in 1%–10% of women during pregnancy.

Women with fibroids are more likely to have pregnancies with complications such as fetal malpresentation, preterm delivery, preterm premature rupture of membranes (PPROM), placenta previa, placental abruption, cesarean delivery, and severe postpartum hemorrhage. Babies born to women with fibroids may weigh less at birth than those born to women without fibroids.

In some studies, when fibroids are larger than 10 cm, adverse outcomes were more common. However, the number of fibroids and their location within the uterus did not affect adverse outcomes.

Approximately 60% of fibroids will grow or shrink by greater than 10% of their original size during pregnancy. Fibroids larger than 5 cm are more likely to grow during pregnancy. Most fibroid growth occurs in the first trimester. A considerable percentage of fibroids (approximately 40%) present in early pregnancy will have gone away and another 75% will be smaller by the time the baby is born.

Fibroid-related pain (red degeneration) occurs in 5%¬15% of patients, and is usually well controlled with painkiller and does not require surgery.

The major risk of pregnancy following myomectomy is uterine rupture either during or before labor. This risk will depend on the size of the uterine incision(s) and the size and number of fibroids removed.