A study performed in 2004 at the University of North Carolina at Chapel Hill found that small uterine fibroids are linked to a higher risk for miscarriage. Uterine fibroids are benign, non-cancerous muscle tumors that affect a woman's uterus. Experts believe that more than one in every five women of reproductive age develops fibroids, though not all of them have noticeable symptoms. Scientists are still gathering data about how such growths affect obstetric outcomes in terms of miscarriage, premature labor and delivery, and intrauterine growth restriction (IUGR).
Lead author of this study, Dr. Katherine Hartmann, assistant professor of obstetrics and gynecology and epidemiology at UNC's schools of medicine and public health says, "No studies have prospectively investigated these risks in a large cohort of women early in pregnancy where presence of fibroids was uniformly assessed using ultrasound imaging. This is the first large-scale prospective study to do that." Hartmann adds that fibroids are very common which means that these poor pregnancy outcomes are having a devastating effect on a large number of couples. It is unfortunate, continues the researcher, that not many studies have been undertaken that might inform health care providers on the topic of the effects of fibroids on pregnancy.
Hartmann says that earlier studies employing data from ultrasounds had a basic flaw, because the patients included in these studies had fibroids that doctors considered a major concern. Doctors chose to study fibroids that measured at least 3 centimeters. However, smaller fibroids were often not even noted. As a result, the studies were skewed according to some imagined, arbitrary classification by which some women, who had smaller fibroids, were deemed as not having fibroids at all.
In Hartmann's pilot study, in which there were 1,600 participants, the scientists discovered that most of those who were found to have fibroids were never told (by their physicians) they had them. The scientists discovered fibroids in 170 of the trial participants.
The pilot study suggests that women who have fibroids have an increased risk for miscarriage of 55% and perhaps of even greater significance, that smaller fibroids pose a greater risk for miscarriage than larger fibroids. The study also found that fibroids can cause miscarriage at any time during early pregnancy.
The team has received a $3 million grant from the National Institute for Child Health and Human Development to continue their work. Hartmann's team will be enrolling another 3,300 women of all ethnicities from 15 counties in North Carolina who are either in the planning stages of pregnancy or are in their first weeks of pregnancy.