I have a small fibroid on my uterus. Should I be worried?

Q: I’m hoping to get pregnant and just found out I have a small fibroid in my uterus. My doctor said not to be worried, but I am. What should I do? 

A: Get a second opinion. While some experts believe uterine fibroids, which are noncancerous tumors, do not cause miscarriage, others say they can. “The key is a fibroid’s location and size,” says William P. Hummel, M.D., a reproductive endocrinologist specializing in miscarriage at the San Diego Fertility Center. The closer it is to the center of the uterus, where a fetus is likely to implant, the more likely it is to cause problems. As for size, any fibroid greater than 5 centimeters—about 2 inches—can be problematic. “A fibroid of this size is very vascular [has a lot of blood vessels],” Hummel explains. “A large fibroid shunts blood flow away from the uterus to fuel its own growth.”
Although your fibroid may be small now, that could change when you become pregnant, making some preventive medicine even more important. “During pregnancy, fibroid growth tends to accelerate,” Hummel says. “A borderline significant fibroid can grow to the point where it jeopardizes the pregnancy.”