Uterine fibroids are a common problem in women that can sometimes affect pregnancy outcome. Fibroids (also called myomas) are benign smooth muscle tumors of the uterus that are present in about 10 % of pregnancies. Most women who have fibroids are asymptomatic throughout pregnancy and have no complications. In about 1/3 of women, fibroids grow during pregnancy due to estrogen and progesterone as well as the increased uterine blood volume that occurs with pregnancy. Larger fibroids are more likely to grow than small ones. Growth of fibroids is most common in the first and second trimesters. The most common symptom of fibroid growth is pain. Rapid growth of fibroids can lead to fibroid degeneration. In this situation, fibroids outgrow their blood supply, which results in part of the fibroid dying, prostaglandin release and pain. Some studies have demonstrated a small increased risk for pregnancy complications in women who have fibroids. These complications include miscarriage, preterm labor and preterm birth, bleeding during pregnancy, dysfunctional labor, cesarean delivery and malpresentation of the baby (a baby that is not head down at the time of delivery). In some women with very large fibroids, there is an increased risk the baby may not grow normally. Thus, increased surveillance of pregnant women with multiple or large fibroids is sometimes performed by Dr. Minior. In women with a history of fibroid related pregnancy complications, fibroid removal prior to pregnancy is sometimes considered for women who plan to have more children. This procedure is called myomectomy. Despite these risks, it is important to remember that most pregnancies where fibroids are present result in normal deliveries and normal babies.