Womb fibroids may cause recurrent miscarriages, research suggests

The study, on women who have suffered three or more miscarriages in a row, is the first firm evidence that fibroids are associated with recurrent miscarriage.

Removing fibroids that distort the womb cavity could lead to a future successful pregnancy – doubling the live birth rate, the findings showed.

The study, in the journal Human Reproduction, follows 20 years of research by a team at the recurrent miscarriage clinic at the University of Sheffield and Sheffield Teaching Hospitals.

Fibroids in or around the womb are benign tumours composed of muscle and fibrous tissue, and have been estimated to occur in 3% to 10% of women.

The new study found the rate of fibroids in women experiencing recurrent miscarriage was 8.2%.

However, not all fibroids may cause problems and need surgery. It was removing submucosal fibroids (those that grow into the middle of the womb, distorting the cavity) that appeared to improve the birth rate.

Some 25 women in the study with these cavity-distorting fibroids had them removed surgically, while 54 women with fibroids that did not distort the cavity had no surgery.

A group of 285 women whose recurrent miscarriages were still unexplained after all investigations acted as a control group.

In the 25 women given surgery, miscarriage rates in subsequent pregnancies during the second trimester fell from 21.7% to 0%.

This translated to an increase in the live birth rate from 23.3% to 52%.

Women were just as likely to suffer miscarriage in the first trimester regardless of whether they had surgery – the impact was in lowering the risk of second trimester miscarriages.

Dr Sotirios Saravelos, clinical research Fellow at the University of Sheffield, said: “This is the first time that it has been shown that removing fibroids that distort the uterine cavity may increase the chances of a subsequent live birth in women with recurrent miscarriages.”

Before any treatment, women with fibroids that distorted the womb cavity had a 21.7% second trimester miscarriage rate compared to an 8% second trimester miscarriage rate for women without fibroids.

During the course of the study, those 54 women whose fibroids did not distort the womb cavity and who had had no surgery were able to improve their pregnancy chances after referral to a dedicated recurrent miscarriage clinic.

Before referral, the miscarriage rate during the second trimester was 17.6% but this fell to 0% after referral.

Live birth rates went up from 20.6% to 70.4% in subsequent pregnancies.

This was similar to results from the 285 women with unexplained recurrent miscarriage.

Research suggests that supporting women via regular visits to a dedicated recurrent miscarriage clinic, regular antenatal scans to check the condition of the baby, reassurance to the mother from the specialist that everything is progressing well and specialist antenatal counselling throughout a pregnancy, can help women with recurrent miscarriage.

Dr Saravelos said: “These results are interesting because they suggest that the finding of fibroids in women with recurrent miscarriage does not necessarily imply that the fibroids are the only cause of the miscarriage. In addition, they suggest that surgical intervention is not the only means whereby patients with recurrent miscarriage benefit from attending a specialised, dedicated clinic.

“However, for women with fibroids that distort the uterine cavity, our work shows that removing the fibroids can eliminate miscarriage during the second trimester and double the live birth rate in subsequent pregnancies.”

The team is now hoping to reproduce their findings in larger studies.

Dr Saravelos said another study is needed with a large number of patients to be randomised between intervention and no intervention.