Scientists have developed a test to identify women with an increased risk of miscarriage, which could pave the way for new treatments to prevent pregnancy loss.
About one in six of all pregnancies are lost, most before 12 weeks, and each miscarriage increases the risk of another one happening.
Until now, most research in this area has focused on the quality of the embryo, with the secrets of the womb lining remaining a missing “black box” in reproductive medicine.
Now the largest study of its kind has discovered that an abnormal process in the womb lining could explain why some women experience miscarriage. The findings could open the door to new ways to help women avoid pregnancy loss.
Scientists at the University of Warwick and the University Hospitals Coventry and Warwickshire NHS trust have discovered that in some women with a history of miscarriage, the womb lining does not react the way it should and become a supportive place for an embryo to implant.
This represented “a key piece of the miscarriage puzzle”, they said, tracing miscarriage risk back to a problem with the womb lining before pregnancy, which may also help explain why some women experience repeated pregnancy loss even with healthy embryos.
Using the findings from the study, the team developed a diagnostic test that can measure signs of a healthy or defective reaction in the womb lining.
The lead author of the study, Dr Joanne Muter, a researcher at Warwick medical school whose work was funded by the baby loss charity Tommy’s, said: “This is about identifying preventable miscarriages. Many women are told they’ve just had ‘bad luck’, but our findings show that the womb itself may be setting the stage for pregnancy loss, even before conception takes place.”
The team analysed about 1,500 biopsies from more than 1,300 women. They found that an essential biological process called the decidual reaction, which prepares the womb lining for pregnancy, often does not work properly in women with a history of miscarriage.
When it does not fully activate, an unstable environment is created that, while still allowing embryos to implant, increases the risk of bleeding and early pregnancy loss, the researchers found.
Crucially, this was not random. The abnormal response in the womb lining recurs across menstrual cycles for some women at a rate far greater than chance would predict. This suggested a consistent, measurable and potentially preventable cause of miscarriage risk, the researchers said.
On the back of the research, the team developed a diagnostic test to measure the molecular signals of a healthy or dysfunctional decidual reaction. The test was piloted in Coventry, England, and has already supported the care of more than 1,000 patients.
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One of the women offered the new test, Holly Milikouris, said the experience was “lifechanging” after she had experienced five miscarriages.
“We felt lost and were beginning to accept that I might never successfully carry a pregnancy,” she said. “The treatments that typically can help women who have experienced miscarriages hadn’t worked for us and each time we tried again we felt like we were rolling a dice with the baby’s life.”
The test revealed her womb lining prepared poorly for pregnancy. After treatment, she and her husband, Chris, had two healthy children, George, now three years old, and 17-month-old Heidi.
“Being given the opportunity to take part in this trial was lifechanging. For the first time the results of my biopsy were normal, and we went on to have not one, but two successful pregnancies,” Milikouris said.
Dr Jyotsna Vohra, the director of research at Tommy’s, said women experiencing the trauma and devastation of recurrent miscarriage were far too often “left without answers”. The test could, she said, “pave the way not only for an explanation in some cases but more importantly for treatments that could prevent future pregnancy losses”.