When do I have to start worrying about the size of my fibroid?

Anon, it's possible you'd get pregnant and carry a baby to term with no complications from your fibroid at all, or it's possible that the fibroid could affect you in some ways. Part of it depends on where it is located. Here are a couple of Q&As written by Dr. Richard Schwarz from Discovery Health:

Q. Will a fibroid tumor complicate my pregnancy?
A. Fibroids usually develop prior to pregnancy, though many women don't know they have one until they have an ultrasound or the fibroid is discovered during a pelvic exam. If you know prior to pregnancy that you have fibroids, ask your doctor whether their size or position could cause problems, and which symptoms to watch for. Most women who have one or more of these noncancerous growths experience no pregnancy complications because of them. For the 10 to 30 percent of pregnant women with fibroids who do end up having complications, the most common is abdominal pain, which occasionally may be accompanied by light vaginal bleeding. The baby is rarely affected unless the bleeding is substantial.

Q. Can a fibroid tumor harm the baby?
A. Probably not. Even if you do experience symptoms, they most likely won't affect the baby. However, your risk of miscarriage and premature delivery does increase slightly if you have fibroids. They occasionally cause the baby to be in an abnormal position for delivery. They can also stall labor, or, if they're located in or near the cervical opening, they may block the baby's passage. All of these (rather rare) problems can increase the likelihood of cesarean delivery.

Q. How will a doctor treat fibroid tumors during pregnancy?
A. Painful fibroids are usually treated with bed rest, ice packs, and — when necessary — medication. Your doctor will recommend the treatment that's safest for you. Symptoms usually subside within a few days. Fibroids sometimes grow larger during pregnancy, due in part to pregnancy hormones. For reasons that are not well understood, a fibroid may also get smaller during pregnancy. Your doctor may recommend ultrasound examinations to see whether your fibroid is growing or likely to cause complications.

It also doesn't appear that fibroids interfere with most women's ability to become pregnant -- they cause a small number of cases of infertility, such as fibroids that block one or both of the fallopian tubes or fibroids that are so large they fill the uterus and block an embryo's ability to implant.

Here's a good overall explainer about fibroids and pregnancy:

http://www.parentingweekly.com/preconception/preconception_information/fibroids.htm

And here's that Discovery Health article:

http://health.discovery.com/centers/pregnancy/americanbaby/fibroids.html

Also, you may find this interesting. It's a summary of the issue by the Pacific Fertility Center in San Francisco:

http://www.infertilitydoctor.com/infertility/fibroids.htm

I am 37. I have one child and we have not decided either way yet about having another. So, I am interested in learning if this will have an impact on me if we do want another one.

Hi, Anon. You ask some great questions about a very common condition.

Our Empowher encyclopedia has some excellent information about fibroids, what causes them, and the symptoms to watch out for:

https://www.empowher.com/media/reference/uterine-fibroids

Your doctor is right to employ the use of "watchful waiting." A fibroid that is not causing symptoms is generally not troublesome, and will shrink later, during menopause. Removal of fibroids won't guarantee that they won't come back; about 50 percent of fibroids that are removed in a myomectomy do return.

Here are two more pages with details about fibroids and treatment, from womenshealth.gov and the Merck Manual:

http://www.4woman.gov/faq/uterine-fibroids.cfm

http://www.merck.com/mmhe/sec22/ch246/ch246a.html

As far as shrinking your fibroid, options change based on whether you are or are not trying to become pregnant. Can I ask how old you are, and if pregnancy is an issue?