Major breakthrough in link between fibroids and miscarriage

Important new findings from a decade long study, have altered traditional medical thinking that uterine fibroids cause miscarriages.

The results of the 10-year-study, led by Vanderbilt University Medical Centre's professor of Obstetrics and Gynaecology Katherine Hartmann, were published yesterday in the American Journal of Epidemiology. Fibroids are common benign uterine masses that can distort the external and internal contour of the uterus. The Health Service Executive say that at least one in four women will develop fibroids at some stage in their life:

"They most often occur in women who are from 30 to 50 years old. Fibroids tend to develop more frequently in women who are of Afro-Caribbean origin and in women who are overweight. It is thought that they occur in heavier women as a result of higher oestrogen levels."

Uterine changes and other local effects of fibroids have, for a long time, been implicated as a risk factor for miscarriage. Professor Hartmann says the research team were stunned by the findings showing no link:

"We find women with fibroids are not at increased risk of miscarriage. Women with fibroids had identical risk of miscarriage as women without fibroids when taking into account other risks for pregnancy loss. We were stunned. This is great news for women. Our results challenge the existing paradigm and have potential to reduce unnecessary surgical intervention."

The study included women from eight urban and suburban communities in three different US states who were planning pregnancies, or in the early weeks of pregnancy. Each woman in the had a standardised ultrasound for fibroids to determine presence, number, size and location in the uterus. Of the more than 5,500 women enrolled, ultrasound detected uterine fibroids in 11 percent, while 89 percent of the study participants did not have fibroids. The chance for miscarriage in both groups was 11 percent. "The key message is that fibroids don't seem to be linked to miscarriage," said Hartmann. The initial goal of the study was to understand which fibroids confer the highest risk of miscarriage in order to determine who might benefit most from surgery to remove the fibroids before a future pregnancy. However, Professor Hartmann says that the surprising results of the study should reassure both women and doctors:

"Loss is remarkably common, but we know very little about the causes. When something bad happens in a pregnancy the first thing women look at is themselves, asking why it happened and what they could have done differently. Now women with fibroids have one less thing to worry about."