Fibroids and Infertility: Is There a Relationship?

Fibroids are overgrowths of tissue in the uterus or womb. They grow from the muscle of the uterine wall and are not cancerous or precancerous. They can extend into the inside (submucosal) or protrude from the outside surface of the uterus (subserosal), and can be found within the muscular wall of the uterus (intramural).

Fibroids are very common. Up to 40 percent of women over 35 years of age have fibroids. Many of these women will have no symptoms at all. The likelihood of symptoms depends on the number, size and location of the fibroids. If symptoms occur, they typically will fall into three main categories: heavy menstrual bleeding, pelvic pressure or pain and problems related to pregnancy and fertility. The more fibroids there are and the larger they are, the more likely the woman will have pain and pressure symptoms. The submucosal fibroids are the ones most likely to cause heavy bleeding. Since fibroids are believed to be hormone-dependent, symptoms tend to decrease when a woman reaches menopause.

The degree to which fibroids cause infertility is controversial. The estimated prevalence of fibroids as the only cause for infertility is only 1 to 2%. This means that for most women with fibroids and infertility, there is at least one other explanation for the infertility. Fibroids can cause infertility by mechanically blocking the sperm from reaching the egg, by altering the contractions of the uterus that help the egg and sperm get together, or by changing the uterine environment so that it is suboptimal for embryos to implant.

Studies have shown that the fibroids most likely to cause infertility are the submucosal fibroids, which are located inside or near the innermost layer of the uterus. Also called the endometrium or the uterine cavity, this layer is the site for embryo implantation and the place where the baby grows for the entire pregnancy. So it makes sense that fibroids in this location could interfere with fertility and pregnancy, and most fertility doctors will recommend that these types of fibroids be removed before you try to conceive. Fibroids in other locations are less likely to cause problems with fertility or pregnancy. In these cases, couples are usually instructed to try to become pregnant without treating the fibroids. If the couple has trouble conceiving, other causes of infertility should be eliminated before treating the fibroids.